Air conditioner

An air conditioner is provided that includes an exhaust heat recovery unit for recovering exhaust heat in a heat transfer medium, a heat transfer medium passage in which the heat transfer medium outputted from the exhaust heat recovery unit flows, an auxiliary heating device, heats the heat transfer medium, an absorption chiller driven by heat of the heat transfer medium, a refrigerant passage, through which a refrigerant outputted from the absorption chiller flows, an indoor unit to which the refrigerant is supplied through the refrigerant passage, a heat transfer medium temperature detector for detecting the temperature of the heat transfer medium flowing through the heat transfer medium passage, a refrigerant temperature detector for detecting the temperature of the refrigerant flowing through the refrigerant passage, and a control portion for controlling an operation of driving the auxiliary heating device.

TECHNICAL FIELD

The present invention generally relates to an air conditioner and, more particularly, to an air conditioner utilizing exhaust heat.

BACKGROUND ART

There have been devised air conditioners adapted to perform cooling, heating, or air-conditioning by utilizing exhaust heat from various heat-producing apparatuses, equipment, and facilities. Among such air conditioners which inventors of the invention devised, an air conditioner for performing at least cooling is devised in such a way as to include an absorption chiller of what is called the heat transfer medium drive type, which is adapted to recover exhaust heat and driven by a heat transfer medium, and as to perform cooling by supplying an indoor unit with a refrigerant cooled by the absorption chiller. Further, an air conditioner for performing at least heating is devised in such a way as to recover exhaust heat and as to perform heating by supplying an indoor unit with a heat transfer medium. Moreover, such air conditioners adapted to perform air-conditioning by utilizing exhaust heat are devised in such a manner as to have an auxiliary heating device for heating a heat transfer medium in a case, in which an amount of exhaust heat from an exhaust heat source is insufficient for performing cooling or heating, by utilizing heat of combustion in a burner or heat from a heater so as to make up for the shortage of heat, and also devised so that the temperature of the heat transfer medium is maintained in a predetermined range by controlling an operation of driving such an auxiliary heating device according to the temperature of the heat transfer medium so that the heat transfer medium always has a sufficient amount of heat.

Meanwhile, even in the case that the amount of exhaust heat is at a level insufficient for maintaining the temperature of the heat transfer medium within the predetermined range during a cooling operation, when the cooling load of the indoor unit is low, the absorption chiller sometimes can sufficiently cool the refrigerant and provide a cooled state by using only such an amount of exhaust heat. In such a case, the air conditioner, which is adapted to maintain the temperature of the heat transfer medium within the predetermined range by controlling the operation of driving the auxiliary heating device according to the temperature of the heating device, consumes energy by unnecessarily heating the heat transfer medium by means of the auxiliary heating device regardless of the cooling load. Therefore, even though the air conditioner is of the type utilizing exhaust heat, the energy-saving capability thereof is degraded.

DISCLOSURE OF INVENTION

The problem to be solved by the invention is to enhance the energy-saving capability of an air conditioner.

To achieve the foregoing object, according to an aspect of the invention, there is provided an air conditioner, which comprises an exhaust heat recovery unit for recovering exhaust heat in a heat transfer medium, a heat transfer medium passage in which the heat transfer medium outputted from the exhaust heat recovery unit flows, an auxiliary heating device, provided in the heat transfer medium passage, for heating the heat transfer medium, an absorption chiller, to which the heat transfer medium passage is connected, to be driven by heat of the heat transfer medium, a refrigerant passage, through which a refrigerant outputted from the absorption chiller flows, an indoor unit to which the refrigerant is supplied through the refrigerant passage, a heat transfer medium temperature detecting means for detecting a temperature of the heat transfer medium flowing through the heat transfer medium passage, a refrigerant temperature detecting means for detecting a temperature of the refrigerant flowing through the refrigerant passage, and a control portion for controlling an operation of driving the auxiliary heating device. In this air conditioner, on startup, the control portion controls an operation of driving the auxiliary heating device according to the temperature of the heat transfer medium, which is detected by the heat transfer medium temperature detecting means. When the temperature of the refrigerant, which is detected by the refrigerant temperature detecting means, is equal to or lower than a predetermined temperature, the control portion decides that a startup operation is completed. Upon completion of the startup operation, the control portion controls an operation of driving the auxiliary heating device according to the temperature of the refrigerant, which is detected by the refrigerant temperature detecting means.

With such a configuration, an operation of driving the auxiliary heating device is controlled according to the temperature of the refrigerant. Thus, when the amount of exhaust heat is sufficient for cooling the refrigerant in the absorption chiller regardless of the temperature of the heat transfer medium, that is, when the temperature of the refrigerant cooled by the absorption chiller is at a level at which the cooling load can be sufficiently cooled, the operation of driving the auxiliary heating device is not performed. Further, on the startup of the air conditioner, it is necessary to change the state of the absorption chiller into a state, in which the refrigerant can be sufficiently cooled as soon as possible, that is, a stationary state by recirculating adsorbent in the adsorption chiller to thereby raise the internal temperature of a regenerator of the absorption chiller. Therefore, increase in the rise time from the startup to a time, at which the state of the refrigerator is changed into the stationary state, is restrained by controlling, on the startup, an operation of driving the auxiliary heating device according to the temperature of the heat transfer medium and by deciding, when the temperature of the refrigerant reaches a predetermined temperature, that the startup operation is completed. Thus, when the temperature of the refrigerant is at a level, which is sufficient for performing cooling, regardless of the temperature of the heat transfer medium, the operation of driving the auxiliary heating device is not performed. Consequently, the energy-saving capability of the air conditioner can be enhanced.

Meanwhile, even during the operation of driving the auxiliary heating device is controlled according to the temperature of the refrigerant during the cooling operation, for example, when the cooling load is small, or when the cooling load intermittently occurs, in the case that the amount of exhaust heat varies by iteratively increasing and decreasing, the temperature of the refrigerant may vary at a temperatures, which is close to a predetermined temperature, in a short time that is several tens of seconds or several minutes. In such a case, the temperature of the refrigerant temporarily rises to a level that is equal to or higher than the set temperature. Then, the temperature of the refrigerant quickly drops to a level that is lower than the set temperature. This results in occurrences of operations, in which the auxiliary heating device stops immediately after driven, and in which the heating value of the auxiliary heating device is decreased just after increased. Thus, in the case that an operation of driving the auxiliary heating device is controlled according to the temperature of the refrigerant during the exhaust heat is recovered and the heat transfer medium is heated, the energy-saving capability is degraded by driving the auxiliary heating device or increasing the heating value of the auxiliary heating device in spite of the state in which the temperature of the refrigerant drops without driving the auxiliary heating device and without increasing the heating value thereof.

To solve this problem, in the case of another air conditioner according to another aspect of the invention, the control portion is constructed in such a way as to control an operation of driving the auxiliary heating device according to the temperature of the refrigerant, which is detected by the refrigerant detecting means, and as to drive the auxiliary heating device or increase the heating value thereof when the temperature of the refrigerant, which is detected by the refrigerant temperature detecting means, is equal to or higher than a predetermined temperature and when the state, in which the detected temperature of the refrigerant is equal to or higher than the predetermined temperature, continues for a predetermined time period.

With such a configuration, even when the temperature of the refrigerant becomes equal to or higher than the predetermined temperature, an operation of driving the auxiliary heating device or changing the heating value thereof is not immediately performed. Instead, after a lapse of a predetermined time period since the temperature of the refrigerant becomes equal to or higher than the predetermined temperature, an operation of driving the auxiliary heating device or changing the heating value thereof is performed. Therefore, in the case that the temperature of the refrigerant becomes lower than the predetermined temperature in the predetermined time period, an operation of driving the auxiliary heating device or changing the heating value thereof is not performed. Thus, the energy consumed in the auxiliary heating device can be reduced. Consequently, the energy-saving capability of the air conditioner can be enhanced still more.

Further, even in the case that during a heating operation, the heating operation is performed by causing the heat transfer medium, in which exhaust heat is recovered, to flow in the indoor unit, and that the amount of exhaust heat from the exhaust heat source repeatedly increases and decreases and thus varies, for example, when a heating load is small or intermittently produced, the temperature of the heat transfer medium sometimes varies at a temperature, which is close to the preset temperature, because an operation of driving the auxiliary heating device or changing the heating value thereof. Even at that time, similarly as the air conditioner performs during the cooling operation, when the temperature of the heat transfer medium temporarily drops to a level, which is equal to or lower than the preset temperature, and then immediately rises to a level that is higher than the preset temperature, the auxiliary heating device may be driven and then quickly stop. Alternatively, the heating value of the heating device may increase once and then immediately decrease. Thus, in the case that an operation of driving the auxiliary heating device is controlled according to the temperature of the heat transfer medium during the exhaust heat is recovered and the heat transfer medium is heated, the energy-saving capability is degraded by driving the auxiliary heating device or increasing the heating value of the auxiliary heating device in spite of the state in which the temperature of the refrigerant rises without driving the auxiliary heating device and without increasing the heating value thereof.

To solve this problem, according to another aspect of the invention, there is provided an air conditioner that comprises an exhaust heat recovery unit for recovering exhaust heat in a heat transfer medium, a heat transfer medium passage in which the heat transfer medium outputted from the exhaust heat recovery unit flows, an auxiliary heating device, provided in the heat transfer medium passage, for heating the heat transfer medium, an absorption chiller, to which the heat transfer medium passage is connected, to be driven by heat of the heat transfer medium, a refrigerant passage, through which a refrigerant outputted from the absorption chiller flows, an indoor unit to which the refrigerant is supplied through the refrigerant passage, a heat transfer medium temperature detecting means for detecting a temperature of the heat transfer medium flowing through the heat transfer medium passage, a refrigerant temperature detecting means for detecting a temperature of the refrigerant flowing through the refrigerant passage, and a control portion for controlling an operation of driving the auxiliary heating device. This control portion controls an operation of driving the auxiliary heating device according to the temperature of the heat transfer medium, which is detected by the heat transfer medium temperature detecting means. During a state in which the heat transfer medium is heated by exhaust heat, the control portion drives the auxiliary heating device or increases a heating value of the auxiliary heating device in the case that a condition, in which the temperature of the heat transfer medium detected by the refrigerant temperature detecting means is equal to or lower than a predetermined temperature, lasts for a predetermined time period.

With such a configuration, even when the temperature of the heat transfer medium becomes equal to or higher than the predetermined temperature, an operation of driving the auxiliary heating device or changing the heating value thereof is not immediately performed. Instead, after a lapse of a predetermined time period since the temperature of the heat transfer medium becomes equal to or higher than the predetermined temperature, an operation of driving the auxiliary heating device or changing the heating value thereof is performed. Therefore, in the case that the temperature of the heat transfer medium becomes lower than the predetermined temperature in the predetermined time period, an operation of driving the auxiliary heating device or changing the heating value thereof is not performed. Thus, the energy consumed in the auxiliary heating device can be reduced. Consequently, the energy-saving capability of the air conditioner can be enhanced.

Moreover, according to another aspect of the invention, there is provided an air conditioner that comprises an exhaust heat recovery unit for recovering exhaust heat in a heat transfer medium, a heat transfer medium passage in which the heat transfer medium outputted from the exhaust heat recovery unit flows, an auxiliary heating device, provided in the heat transfer medium passage, for heating the heat transfer medium, an absorption chiller, to which the heat transfer medium passage is connected, to be driven by heat of the heat transfer medium, a refrigerant passage, through which a refrigerant outputted from the absorption chiller flows, an indoor unit to which the refrigerant is supplied through the refrigerant passage, a heat transfer medium temperature detecting means for detecting a temperature of the heat transfer medium flowing through the heat transfer medium passage, a refrigerant temperature detecting means for detecting a temperature of the refrigerant flowing through the refrigerant passage, and a control portion for controlling an operation of driving the auxiliary heating device. In this air conditioner, on startup of a cooling operation, the control portion controls an operation of driving the auxiliary heating device according to the temperature of the heat transfer medium, which is detected by the heat transfer medium temperature detecting means. When the temperature of the refrigerant, which is detected by the refrigerant temperature detecting means, is equal to or lower than a first temperature, the control portion decides that the startup of a cooling operation is completed. Upon completion of the startup of the cooling operation, the control portion controls an operation of driving the auxiliary heating device according to the temperature of the refrigerant, which is detected by the refrigerant temperature detecting means. During a state in which the heat transfer medium is heated by exhaust heat, the control portion drives the auxiliary heating device or increases a heating value of the auxiliary heating device in the case that the temperature of the heat transfer medium detected by the refrigerant temperature detecting means is equal to or lower than a second temperature, which is higher than the first temperature, and that a condition, in which the temperature of the heat transfer medium detected by the refrigerant temperature detecting means is equal to or lower than the second temperature, lasts for a predetermined time period. With such a configuration, which is preferable, the energy-saving capability of this air conditioner can be enhanced still more without increasing the rise time.

Furthermore, according to another aspect of the invention, there is provided an air conditioner that comprises an exhaust heat recovery unit for recovering exhaust heat in a heat transfer medium, a heat transfer medium passage in which the heat transfer medium outputted from the exhaust heat recovery unit flows, an auxiliary heating device, provided in the heat transfer medium passage, for heating the heat transfer medium, an absorption chiller, to which the heat transfer medium passage is connected, to be driven by heat of the heat transfer medium, a refrigerant passage, through which a refrigerant outputted from the absorption chiller flows, a valve provided with the heat transfer medium passage, a bypass passage branching off the valve, an indoor unit to which the refrigerant is supplied through one of bypass passage and the refrigerant passage, a heat transfer medium temperature detecting means for detecting a temperature of the heat transfer medium flowing through the heat transfer medium passage, a refrigerant temperature detecting means for detecting a temperature of the refrigerant flowing through the refrigerant passage, and a control portion for controlling an operation of driving the auxiliary heating device. In this air conditioner, during a cooling operation, the control portion controls an operation of driving the auxiliary heating device according to the temperature of the refrigerant, which is detected by the refrigerant temperature detecting means. During a state in which the heat transfer medium is heated by exhaust heat, the control portion drives the auxiliary heating device or increases a heating value of the auxiliary heating device in the case that the temperature of the refrigerant detected by the refrigerant temperature detecting means is equal to or lower than a first temperature, and that a condition, in which the temperature of the refrigerant detected by the refrigerant temperature detecting means is equal to or lower than the first temperature, lasts for a first time period. During a heating operation, the control portion controls an operation of driving the auxiliary heating device according to the temperature of the heat transfer medium, which is detected by the heat transfer medium temperature detecting means. Moreover, during a state in which the heat transfer medium is heated by exhaust heat, the control portion drives the auxiliary heating device or increases a heating value of the auxiliary heating device in the case that the temperature of the heat transfer medium detected by the heat transfer medium temperature detecting means is equal to or lower than a second temperature, which is higher than the first temperature, and that a condition, in which the temperature of the heat transfer medium detected by the refrigerant temperature detecting means is equal to or lower than the second temperature, lasts for a second time period. With such a configuration, which is preferable, the energy-saving capability of the air conditioner enabled to perform air-conditioning can be enhanced.

BEST MODE FOR CARRYING OUT THE INVENTION

FIRST EMBODIMENT

Hereinafter, a first embodiment of an air conditioner, to which the invention is applied, is described with reference toFIGS. 1 to 3B.FIG. 1is a schematic diagram illustrating the configuration and operation of the first embodiment of the air conditioner to which the invention is applied.FIG. 2is a schematic diagram illustrating the configuration and operation of an absorption chiller of the air conditioner that is the first embodiment to which the invention is applied.

FIG. 3Ais a diagram illustrating an operation of an auxiliary heating device in the case that there is no exhaust heat from an exhaust heat source during a cooling operation.FIG. 3Bis a diagram illustrating an operation of the auxiliary heating device in the case that there is exhaust heat from the exhaust heat source during a cooling operation. Incidentally, in the following description of this embodiment, the air conditioner designed specifically for cooling is described by way of example.

The air conditioner1of this embodiment comprises an exhaust heat recovery unit3, heat transfer medium pipes5a,5b, an auxiliary boiler7serving as an auxiliary heating device, an absorption chiller9, refrigerant pipes11a,11b, an indoor unit13, a heat transfer medium temperature sensor15, a refrigerant temperature sensor17, and a control portion19, as shown inFIG. 1. The exhaust heat recovery unit3has a heat exchange portion21including a pipe, through which the heat transfer medium, such as water, flows. The exhaust heat recovery unit3recovers exhaust heat, which outputted from the exhaust heat source, such as an engine, in the heat transfer medium contained in the heat exchange portion21. The heat transfer medium pipes5aand5bare operative to recirculate the heat transfer medium between the exhaust heat recovery unit3and the absorption chiller9. In the heat transfer medium pipe5a, the heat transfer medium heated by recovering exhaust heat in the heat exchanging portion21of the exhaust heat recovery unit3, while the heat transfer medium radiating heat in the absorption chiller9flows through the heat transfer medium pipe5b.

The heat transfer medium pipe5ais provided with an auxiliary boiler7. A heat transfer medium temperature sensor15for detecting the temperature of the heat transfer medium flowing out of the auxiliary boiler7, and a heat transfer medium pump23for causing the heat transfer medium to flow in the heat transfer medium pipes5aand5bare provided at a portion located at the downstream side of a flow of the heat transfer medium from the auxiliary boiler7of the heat transfer medium pipe5a. A three-way valve25is provided at a portion located at the upstream side of the flow of the heat transfer medium from the auxiliary boiler7and in an outlet portion from the exhaust heat recovery unit3. A non-heat-recovery pipe27is provided between the three-way valve25and an inlet portion to the exhaust heat recovery unit3of the heat transfer medium pipe5b. That is, the non-heat-recovery pipe27is connected to the three-way valve25at an end thereof and also connected to the inlet portion to the exhaust heat recovery unit3at the other end.

The auxiliary boiler7has a burner (not shown). The heat transfer medium is heated by combustion in this burner. The absorption chiller9is of the heat transfer medium drive type that has a regenerator for heating adsorbent by heat of the heat transfer medium. The heat transfer medium pipes5aand5bare connected to the heat exchanger29that is provided in the regenerator of the absorption chiller9and that serves as a passage for the heat transfer medium. Further, the absorption chiller9has a cooling water pipe and a cooling tower (not shown) in which cooling water to be used in a condenser of the absorption chiller9is circulated. Refrigerant pipes11aand11bare used for circulating the refrigerant, for example, water between the absorption chiller9and the indoor unit13, and connected to a heat exchanger31that is provided in an evaporator of the absorption chiller9and that serves as a passage for the refrigerator. In the refrigerant pipe11a, the refrigerant cooled by the absorption chiller9is caused to flow, while in the refrigerant pipe11b, the refrigerant undergoing heat exchange in the indoor unit13is caused to flow. The refrigerant pipe11ais provided with the refrigerant temperature sensor17for detecting the temperature of the refrigerant flowing out of the absorption chiller9, and a refrigerant pump33for causing the refrigerant to flow in the refrigerant pipes11aand11bin sequence.

The control portion19is electrically connected to the three-way valve25, the auxiliary boiler7, the heat transfer medium temperature sensor15, the heat transfer medium pump23, a pump (not shown) for causing the cooling water to flow therethrough and a pump (not shown) for causing the adsorbent to flow therethrough, which are provided in the absorption chiller9, the refrigerant temperature sensor17, the refrigerant pump33, and a control part (not shown) of the indoor unit13through wires35. Further, the control portion19is also electrically connected to a control part (not shown) of the engine serving as the exhaust heat source through wires (not shown), and receives information indicating whether or not the exhaust heat source is driven and operates.

Hereinafter, the configuration of the absorption chiller9of this embodiment is described. As illustrated inFIG. 2, the absorption chiller9of this embodiment comprises a regenerator37, a condenser39, an evaporator41, and an absorber43. The regenerator37contains the heat exchanger29that is connected to the heat transfer medium pipes5aand5b, and that permits the heat transfer medium to flow therethrough. A spraying portion45for spraying diluted solution onto the heat exchanger29is provided above the heat exchanger29. A diluted solution pipe47, through which the diluted solution generated in the absorber43flows, is connected to the spraying portion45. A concentrated solution pipe49for introducing a concentrated solution, which is accumulated in the bottom portion of the regenerator37, to the absorber43is connected to the bottom portion of the regenerator37. Furthermore, the regenerator37is provided in such a manner as to communicate with the condenser39so that vapor generated in the regenerator37can flow thereinto.

The condenser39contains a heat exchanger51, into which cooling water cooled in a cooling tower (not shown) flows. A cooling water pipe53is connected to the heat exchanger51so that the cooling water can be circulated between the heat exchanger51and the cooling tower (not shown). Further, a refrigerant pipe55a, in which refrigerant liquid accumulated in the bottom portion of the condenser39flows, is connected to the bottom portion of the condenser39at an end thereof and also connected to a spraying portion57for spraying the refrigerant liquid onto the heat exchanger31provided in the evaporator41at the other end thereof. Moreover, a refrigerant liquid amount adjusting pipe55bfor adjusting an amount of the sprayed refrigerant liquid in the evaporator41is connected to the bottom portion of the condenser39at an end thereof in parallel with the refrigerant liquid pipe55a, and also connected to the spraying portion57provided in the evaporator41at the other end thereof together with the refrigerant liquid pipe55a. A refrigerant liquid amount adjusting valve58for adjusting the flow rate of the refrigerant is provided in the refrigerant liquid amount adjusting pipe55b. In the evaporator41, a heat exchanger31connected to the refrigerant pipes11aand11bfor sending a cooling refrigerant to the indoor unit13is provided. The spraying portion57is provided above the heat exchanger31. Further, the evaporator41is provided in such a way as to communicate with the absorber43so that the vapor generated in the evaporator41can flow therethrough.

The absorber43contains a heat exchanger59through which the cooling water cooled by the cooling tower (not shown). The cooling water pipe53is connected to the heat exchanger59of the absorber43in such a manner as to enable the cooling water to circulate between the heat exchanger59and the cooling tower (not shown). A spraying portion61for spraying concentrated solution generated in the regenerator37onto the heat exchanger59is provided above the heat exchanger59of the absorber43. A concentrated solution pipe49is connected to the spraying portion61. Further, a diluted solution pipe47, through which diluted solution, which is accumulated in the bottom portion of the absorber43, flows, is connected to the bottom portion of the absorber43. The diluted solution pipe47is provided with a pump63that sends the diluted solution to the spraying portion45of the regenerator37. Furthermore, the heat exchanger51of the condenser39and the heat exchanger59of the absorber43are provided in series to the cooling water53. The cooling water cooled by the cooling tower (not shown) flows through the heat exchanger59of the absorber43and the heat exchanger51of the condenser39in sequence and thus circulates therebetween. A heat exchange65for performing heat exchange between the diluted solution contained in the diluted solution pipe47and the concentrated solution contained in the concentrated solution pipe49is provided between the pump63provided in the diluted solution pipe47and the regenerator37.

In the air conditioner1of such a condition of this embodiment, when there is a request to air-condition and the commencement of a cooling operation is directed, the control portion19starts a cooling startup operation. In the cooling startup operation, the heat transfer medium pump23and the refrigerant pump33are operated so that the heat transfer medium and the cooling water flow through the absorption chiller9and circulate through the heat transfer medium pipes5aand5band the refrigerant pipes11aand11b. Moreover, the pump63of the absorption chiller9and a cooling fan of the cooling tower (not shown) are operated. At that time, the control portion19controls combustion in the auxiliary boiler7according to the temperature of the heating medium, which is detected by the heat transfer medium temperature sensor15. That is, the heat transfer medium is heated by utilizing the exhaust heat recovered by the exhaust heat recovery unit3and the combustion performed in the auxiliary boiler7until the temperature of the heat transfer medium reaches a preset temperature Th1. When the temperature of the heat transfer medium becomes equal to or higher than the predetermined temperature Th1, the control portion19stops the combustion in the auxiliary boiler7. During this time period, the control portion19detects the temperature of the refrigerant by use of the refrigerant temperature sensor17. When the refrigerant cooled by the absorption chiller9reaches the preset temperature Tc1, the control portion19decides that the cooling startup operation is completed. Thus, the air conditioner is put into a cooling stationary operation mode. Incidentally, inFIG. 1, solid arrows indicate the directions in which the heat media flow, while dashed arrows indicate directions in which the refrigerants flow.

When the air conditioner starts a cooling stationary operation, the control portion19controls the combustion in the auxiliary boiler7according to the temperature of the refrigerant, which is detected by the refrigerant temperature sensor17. At that time, in the case that there is no exhaust heat, for example, the case that the exhaust heat source is stopped, the control portion19the combustion in the auxiliary boiler7within the range of the temperature of the refrigerant, which ranges from Tc2to Tc5. Incidentally, it is assumed herein that Tc2<Tc3<Tc4<Tc5. When the temperature of the refrigerant rises owing to increase in the cooling load and the value thereof detected by the refrigerant temperature sensor17reaches Tc4, the control portion19turns on the burner (not shown) of the auxiliary boiler7and starts the combustion in a low combustion mode and heats the heat transfer medium. In the case that thereafter, the temperatures of the refrigerant keeps rising, and that the temperature of the refrigerant, which is detected by the refrigerant temperature sensor, reaches Tc5, the control portion19changes the mode of the combustion from the low combustion mode to a high combustion mode, and also increases the heating value. Thus, the temperature of the heat transfer medium rises, and the refrigerant is sufficiently cooled by the absorption chiller9. Consequently, the temperature of the refrigerant falls down. When the temperature of the refrigerant, which is detected by the refrigerant temperature sensor17, reaches Tc3, the control portion19changes the combustion mode of the auxiliary boiler7from the high combustion mode to the low combustion mode, and reduces the heating value thereof. Even after the heating value is reduced, the temperature of the refrigerant keeps dropping. When the temperature of the refrigerant, which is detected by the refrigerant temperature sensor17reaches Tc2, the control portion19turns off the burner (not shown) of the auxiliary boiler17and stops the heating of the heat transfer medium.

In the case that the exhaust heat source is operated, and that the heat transfer medium can be heated by exhaust heat, as shown inFIG. 3B, the control portion19controls the combustion in the auxiliary boiler7within the range of the temperature of the refrigerant, which ranges from Tc3to Tc7. Incidentally, it is assumed herein that Tc3<Tc5<Tc6<Tc7, and that Tc4<Tc5. When the temperature of the refrigerant rises owing to increase in the cooling load and to variation in the amount of the heat, and the temperature thereof detected by the refrigerant temperature sensor17reaches Tc5, the control portion19performs measurement of length of a time. When a condition, in which the temperature of the refrigerant detected by the refrigerant temperature sensor17is equal to or higher than Tc5, lasts for a time period tm1, that is, when a time period tm1lapses after the temperature of the refrigerant becomes equal to or higher than Tc5, the control portion19turns on the burner (not shown) of the auxiliary boiler7and starts the combustion therein in the low combustion mode and heats the heat transfer medium. Alternatively, when the temperature of the refrigerant keeps rising and reaches Tc6, the control portion19turns on the burner (not shown) of the auxiliary boiler7regardless of a time period lapsed since the detected temperature of the refrigerant reaches Tc5. Then, the control portion19starts the combustion therein in the low combustion mode and heats the heat transfer medium. In other words, when the temperature of the refrigerant reaches Tc6, or when a condition, in which the temperature of the refrigerant is equal to or higher than Tc5and less than Tc6, lasts for a time period tm1, the control portion19turns on the burner (not shown) of the auxiliary boiler7and starts the combustion therein in the low combustion mode and heats the heat transfer medium.

In the case that thereafter, the temperature of the refrigerant does not become less than Tc5and that a condition, in which the temperature of the refrigerant is equal to or higher than Tc5, lasts for a time period tm2(incidentally, in this embodiment, it is assumed that tm1=tm2/2), that is, when the time period tm2elapses since the temperature of the refrigerant becomes equal to or higher than Tc5, the control portion19changes the mode of the combustion in the auxiliary boiler7from the low combustion mode to the high combustion mode, and increases the heating value thereof. Alternatively, when the temperature of the refrigerant keeps rising and reaches Tc7, the control portion19turns on the burner (not shown) of the auxiliary boiler7regardless of a time period lapsed since the detected temperature of the refrigerant reaches Tc5. Then, the control portion19changes the mode of combustion therein from the low combustion mode to the high combustion mode, and increases the heating value thereof. In other words, when the temperature of the refrigerant reaches Tc7, or when a condition, in which the temperature of the refrigerant is equal to or higher than Tc5and less than Tc7, lasts for a time period tm2, the control portion19changes the mode of combustion in the auxiliary boiler7from the low combustion mode to the high combustion mode, and increases the heating value thereof. Thus, the temperature of the heat transfer medium rises. The refrigerant is sufficiently cooled by the absorption chiller9. Then, the temperature of the refrigerant falls down. When the temperature of the refrigerant, which is detected by the refrigerant temperature sensor17, reaches Tc3, the control portion19turns off the burner (not shown) of the auxiliary boiler7, and stops the heating of the heat transfer medium. Incidentally, in this embodiment, it is assumed that Tc3=Tc1.

Incidentally, during the cooling stationary operation, the control portion19controls an operation of the auxiliary boiler7according to the temperature of the refrigerant. Further, the control portion19detects the temperature of the heat transfer medium by using the heat transfer medium temperature sensor15. Moreover, when the temperature of the heat transfer medium reaches an overtemperature Th2(incidentally, it is assumed that Th1<Th2), when combustion is performed in the auxiliary boiler7, the control portion19stops the combustion. Further, as illustrated inFIG. 1, the three-way valve25is switched, so that a part of the heat transfer medium flowing through the heat transfer medium pipe5ais caused to flow into the non-heat-recovery pipe27. Thus, the recovery of exhaust heat into the heat transfer medium is stopped by the control portion19. Consequently, an occurrence of overheat of the heat transfer medium is prevented.

Further, When the temperature of the heat transfer medium reaches the overtemperature Th2, the internal temperature of the regenerator3of the absorption chiller9becomes excessively high. Thus, the adsorbent contained in the regenerator37is put into an overconcentrated state. Consequently, the component of the material of the adsorbent may be crystallized. This may impede an operation of driving the absorption chiller9. Therefore, when the temperature of the heat transfer medium reaches the overtemperature Th2, the control portion19completely opens the refrigerant liquid amount adjusting valve58of the refrigerant liquid amount adjusting pipe55bregardless of the temperature of the refrigerant used for cooling, which flows through the refrigerant pipe11a, and the internal temperature of the evaporator41. Further, the control portion19discharges the refrigerant liquid accumulated in the bottom portion of the condenser39into the evaporator41, and thus reduces the concentration of the diluted solution sent to the regenerator37through the diluted solution pipe47.

Thus, in the case of the air conditioner1of this embodiment, during the cooling stationary operation, an operation of the auxiliary boiler7is controlled according to the temperature of the refrigerant, which is detected by the refrigerant temperature sensor17. Therefore, regardless of the temperature of the heat transfer medium, when the temperature of the refrigerant is sufficient for cooling, the auxiliary boiler7does not operate. Furthermore, in the case that the combustion in the auxiliary boiler7is controlled according to the temperature of the heat transfer medium, when the temperature of the heat transfer medium, in which exhaust heat is recovered, is slightly lower than a preset temperature, and even when the heating value thereof is sufficient for cooling the refrigerant in the absorption chiller9, the auxiliary boiler7is driven and operates. Thus, the temperature of the heat transfer medium quickly becomes higher than the overtemperature. Then, the three-way valve25is switched, so that the recovery of exhaust heat to the heat transfer medium is not performed. Consequently, sometimes, the exhaust heat is not effectively utilized. However, in the case of the air conditioner1of this embodiment, an operation of the auxiliary boiler7is controlled according to the temperature of the refrigerant, which is detected by the refrigerant temperature sensor17. Thus, in the case that the amount of exhaust heat is sufficient for cooling the refrigerant in the absorption chiller9and that the refrigerant is cooled to a temperature necessary for cooling, the auxiliary boiler7does not operate. Consequently, the three-way valve25is hard to switch. This embodiment can continue to perform the recovery of exhaust heat into the heat transfer medium can be continued. Moreover, the exhaust heat can be effectively utilized. Therefore, when the temperature of the refrigerant is sufficient for performing a cooling operation regardless of the temperature of the heat transfer medium, the auxiliary boiler7does not consume energy. Furthermore, the three-way valve25is hard to switch. Additionally, this embodiment can continue to perform the recovery of exhaust heat into the heat transfer medium. Thus, the energy-saving capability of the air conditioner can be enhanced.

Furthermore, when a cooling operation startup of the conventional air conditioner is performed, it is necessary to raise the temperature of the heat transfer medium to a temperature, at which the absorption chiller9can be driven, as soon as possible by operating the auxiliary boiler7regardless of the amount of exhaust heat in such a manner as to provide a maximum output thereof. In contrast, in the case of the air conditioner1of this embodiment, during the cooling operation startup thereof, the combustion in the auxiliary boiler7is controlled according to the temperature of the heat transfer medium. Thus, the temperature of the heat transfer medium can be raised to a sufficient level, at which the absorption chiller is driven, as soon as possible, irrespective of the refrigerant.

Additionally, in the case that the heat transfer medium is heated by exhaust heat outputted from the exhaust heat source in the air conditioner1of this embodiment, when the time period tm1elapsed since the temperature of the refrigerant becomes equal to or higher than Tc5, the burner (not shown) of the auxiliary boiler7is turned on. Moreover, the combustion therein is started in the low combustion mode. Furthermore, when the time period tm2(incidentally, tm1<tm2) elapses since the temperature of the refrigerant becomes equal to or higher than Tc5, the combustion mode of combustion in the auxiliary boiler7is changed from the low combustion mode to the high combustion mode, so that the heating value thereof is increased. Therefore, when the amount of exhaust heat outputted from the exhaust heat source easily varies, for example, when the cooling load is small, or when the cooling load occurs intermittently, or when a valve for controlling the amount of the refrigerant flowing into the indoor unit13repeats opening/closing operations, the amount of exhaust heat supplied from the exhaust heat source varies by repeating increase/decrease thereof. Thus, even when the temperature of the refrigerant temporarily rises in spite of the fact that the temperature of the refrigerant is generally liable to drop or to be unchanged, the auxiliary boiler7is restrained from starting combustion therein. Moreover, the heating value of the auxiliary boiler7is prevented from increasing. Thus, the energy consumption of the auxiliary boiler7is limited. Consequently, the energy-saving capability of the air conditioner can be enhanced.

Furthermore, in the case of the air conditioner1of this embodiment, independently of the duration of the condition, in which the temperature of the refrigerant is equal to or less than Tc5, the heating value of the auxiliary boiler7is increased when the temperature of the refrigerant reaches a temperature being close to a temperature at which the sufficient cooling performance of the indoor unit13cannot be obtained, that is, when the temperature of the refrigerant reaches Tc7. Thus, the temperature of the refrigerant can be prevented from rising to a temperature at which the sufficient cooling performance of the indoor unit13cannot be obtained. Consequently, this embodiment is preferable, because the comfort of the air conditioner is not lost.

Further, in the case of the air conditioner1of this embodiment, when the temperature of the heat transfer medium becomes equal to or higher than the overtemperature Th2, the absorption chiller9completely opens the refrigerant liquid amount adjusting valve58and lower the concentration of the diluted solution to be sent to the regenerator37. Thus, an occurrence of crystallization due to the overconcentration of the concentrated solution in the regenerator37can be prevented. Therefore, inconvenience owing to overheat of the heat transfer medium is hard to occur in the absorption chiller9. Consequently, the reliability of the air conditioner can be enhanced.

SECOND EMBODIMENT

A second embodiment of the air conditioner, to which the invention is applied, is described hereinbelow with reference toFIG. 4toFIG. 5B.FIG. 4is a schematic diagram illustrating the configuration and operation of the second embodiment of the air conditioner to which the invention is applied.FIG. 5Ais a diagram illustrating an operation of an auxiliary heating device in the case that there is no exhaust heat from an exhaust heat source during a heating operation.FIG. 5Bis a diagram illustrating an operation of the auxiliary heating device in the case that there is exhaust heat from the exhaust heat source during a heating operation. Incidentally, constituent elements of this embodiment, which are the same as those of the first embodiment, are designated by the same reference characters used for denoting the same constituent elements of the first embodiment. Further, the description of such constituent element is omitted herein. Hereunder, constituent elements and features of the second embodiment, which differ from those of the first embodiment, are described.

The different between the air conditioners of the first and second embodiments resides in that the air conditioner of the second embodiment has no absorption chiller, and that the air conditioner of this embodiment is used only for heating. That is, an air conditioner67of this embodiment comprises the exhaust heat recovery unit3, heat transfer medium pipes69aand69b, the auxiliary boiler7serving as the auxiliary heating device, the indoor unit13, the heat transfer medium temperature sensor15, and the control portion19. The heat transfer medium pipes69aand69bare used for circulating the heat transfer medium between the exhaust heat recovery unit3and the indoor unit13. The heat transfer medium, in which exhaust heat is recovered by the exhaust heat recovery unit3, flows in the heat transfer medium pipe69a. Conversely, the heat transfer medium discharging heat in the indoor unit13flows in the heat transfer medium pipe69b. The heat transfer medium pipe69a, in which the heat transfer medium flows, is provided with the auxiliary boiler7, the heat transfer medium pump23, and the heat transfer medium temperature sensor15, which are serially provided in this order from the side of the exhaust heat recovery unit3.

The control portion19is electrically connected to the three-way valve25, the auxiliary boiler7, the heat transfer medium pump23, the heat transfer medium temperature sensor15, and a control part (not shown) of the indoor unit13through the wires35. Further, the control portion19is also electrically connected to a control part (not shown) of the engine serving as the exhaust heat source through wires (not shown), and receives information indicating whether or not the exhaust heat source is driven and operates.

In the air conditioner1of such a configuration of this embodiment, when there is a request to air-condition and the commencement of a heating operation is directed, the control portion19starts a heating operation. In the heating operation, the heat transfer medium pump23is operated so that the heat transfer medium circulates through the heat transfer medium pipes69aand69b. At that time, the control portion19controls the combustion in the auxiliary boiler7according to the temperature of the heat transfer medium, which is detected by the heat transfer medium temperature sensor15. At that time, in the case that there is no exhaust heat, for example, the case that the exhaust heat source is stopped, the control portion19the combustion in the auxiliary boiler7within the range of the temperature of the refrigerant, which ranges from Th3to Th6, as illustrated inFIG. 5A. Incidentally, it is assumed herein that Th3<Th4<Th5<Th6. Moreover, it is assumed that Th6<Th1<Th2.

During the heating operation startup, or when the heating load is large and the temperature of the heating medium is equal to or less than Th3, the control portion19drives the auxiliary boiler7in the high combustion mode. Then, the temperature of the heat transfer medium rises. When the temperature of the heat transfer medium detected by the heat transfer medium temperature sensor15reaches Th5, the control portion19changes the combustion mode of the auxiliary boiler7from the high combustion mode to the low combustion mode and thus reduces the heating value thereof. Then, the temperature of the heat transfer medium still rises. When the temperature of the heat transfer medium detected by the heat transfer medium temperature sensor15reaches Th6, the control portion19turns off the burner (not shown) of the auxiliary boiler7and stops the heating of the heat transfer medium. When the temperature of the heat transfer medium lowers and the temperature thereof detected by the heat transfer medium temperature sensor15reaches Th4, the control portion19turns on the burner (not shown) of the auxiliary boiler7and starts combustion therein in the low combustion mode and heats the heat transfer medium. Even though the heating of the heat transfer medium in the low combustion mode is performed by the auxiliary boiler7, the temperature of the heat transfer medium drops. When the temperature of the refrigerant, which is detected by the heat transfer medium temperature sensor15reaches Th3, the control portion19changes the combustion mode of the auxiliary boiler7from the low combustion mode to the high combustion mode and increases the heating value thereof.

In the case that the exhaust heat source is operated, and that the heat transfer medium can be heated by exhaust heat, as shown inFIG. 5B, the control portion19controls the combustion in the auxiliary boiler7within the range of the temperature of the refrigerant, which ranges from Th3to Th7. Incidentally, it is assumed herein that Th7<Th3<Th4<Th5<Th6. During the heating operation startup, or when the heating load is large and the temperature of the heating medium is equal to or less than Th3, the control portion19heats the heat transfer medium by driving the auxiliary boiler7in the high combustion mode. Then, the temperature of the heat transfer medium rises. When the temperature of the heat transfer medium detected by the heat transfer medium temperature sensor15reaches Th5, the control portion19changes the combustion mode of the auxiliary boiler7from the high combustion mode to the low combustion mode and reduces the heating value thereof. The temperature of the heat transfer medium is lowered by reducing the heating value of the auxiliary boiler7. When the temperature f the refrigerant detected by the heat transfer medium temperature sensor15reaches Th3, the control portion19changes the combustion mode of the auxiliary boiler7from the low combustion mode to the high combustion mode and increases the heating value thereof. Even when the heating value of the auxiliary boiler7is reduced, the temperature of the heat transfer medium rises. When the temperature of the refrigerant detected by the heat transfer medium temperature sensor15reaches Th6, the control portion19turns off the burner (not shown) of the auxiliary boiler7, so that the combustion therein is stopped, and stops the heating of the heat transfer medium.

The temperature of the heat transfer medium is lowered owing to increase in the heating load and to reduction in the amount of exhaust heat. When the temperature detected by the heat transfer medium temperature sensor15reaches Th4, the control portion19performs measurement of a time. When a condition, in which the temperature of the heat transfer medium detected by the heat transfer medium temperature sensor15is equal to or less than Th4, lasts for a time period tm3, that is, when the time period tm3elapses since the temperature of the refrigerant becomes equal to or higher than Th4, the control portion19turns on the burner (not shown) and starts combustion therein in the low combustion mode, and heats the heat transfer medium. Alternatively, in the case that the temperature of the heat transfer medium continues to drop, when the temperature of the heat transfer medium reaches Th7, the control portion19turns on the burner (not shown) of the auxiliary boiler7, regardless of the time period elapsed since the temperature of the heat transfer medium reaches Th4. Then, the control portion19starts combustion therein in the low combustion mode, and heats the heat transfer medium. In other words, when the temperature of the heat transfer medium reaches Th7, or in the case that a condition, in which the temperature of the heat transfer medium is equal to or higher than Th4and less than Th7, lasts for the time period tm3, the control portion19turns on the burner (not shown) of the auxiliary boiler7and starts combustion therein in the low combustion mode, and heats the heat transfer medium.

Incidentally, the highest temperature Th6in the range of the temperature of the heat transfer medium, which is set for performing a control operation in this embodiment, is set at a value at which the indoor unit13is not thermally damaged when the heat transfer medium flows into the indoor unit13. Further, when the temperature of the heat transfer medium reaches an overtemperature Th8(incidentally, it is assumed that Th7<Th8<Th1) being close to a temperature, at which the indoor unit13may be thermally damaged, the control portion19stops the combustion in the case that the auxiliary boiler7performs combustion. Moreover, as illustrated inFIG. 4, the three-way valve25is switched, so that a part of the heat transfer medium flowing through the heat transfer medium pipe69ais caused to flow into the non-heat-recovery pipe27. Thus, the recovery of exhaust heat into the heat transfer medium is stopped by the control portion19. Consequently, the indoor unit is prevented from being thermally damaged.

Thus, according to the air conditioner67of this embodiment, in the case that the heat transfer medium is heated by exhaust heat outputted from the exhaust heat source, the control portion turns on the burner (not shown) of the auxiliary boiler7when the time period tm3elapses since the temperature of the refrigerant becomes equal to or less than Tc4. Then, the control portion starts combustion therein in the low combustion mode. Therefore, when the amount of exhaust heat outputted from the exhaust heat source easily varies, for example, when the cooling load is small, or when the cooling load occurs intermittently, or when a valve for controlling the amount of the refrigerant flowing into the indoor unit13repeats opening/closing operations owing to a partial load, the amount of exhaust heat supplied from the exhaust heat source varies by repeating increase/decrease thereof. Thus, even when the temperature of the refrigerant temporarily rises in spite of the fact that the temperature of the refrigerant is generally liable to drop or to be unchanged, the auxiliary boiler7is restrained from starting combustion therein. Moreover, the heating value of the auxiliary boiler7is prevented from increasing. Thus, the energy consumption of the auxiliary boiler7is limited. Consequently, the energy-saving capability of the air conditioner can be enhanced.

Furthermore, in the case of the air conditioner1of this embodiment, independently of the duration of the condition, in which the temperature of the refrigerant is equal to or less than Th4, the auxiliary boiler7is operated when the temperature of the refrigerant reaches a temperature being close to a temperature at which the sufficient heating performance of the indoor unit13cannot be obtained, that is, when the temperature of the heat transfer medium reaches Th7. Thus, the temperature of the heat transfer medium can be prevented from falling to a temperature at which the sufficient heating performance of the indoor unit13cannot be obtained. Consequently, this embodiment is preferable, because the comfort of the air conditioner is not lost.

Additionally, in the foregoing description of this embodiment, the configuration of the air conditioner, in which combustion in the auxiliary boiler7is started when a condition, in which the temperature of the heat transfer medium is equal to or less than the predetermined temperature, lasts for the predetermined time period has been described. However, the air conditioner of this embodiment may have a configuration in which the heating value of the auxiliary boiler7is increased when a condition, in which the temperature of the heat transfer medium is equal to or less than the predetermined temperature during the heating operation, lasts for the predetermined time period. Alternatively, the air conditioner of the invention may employ the combination of such configurations.

THIRD EMBODIMENT

A third embodiment of the air conditioner, to which the invention is applied, is described hereinbelow with reference toFIG. 6.FIG. 6is a schematic diagram illustrating the configuration and operation of the third embodiment of the air conditioner to which the invention is applied. Incidentally, constituent elements of this embodiment, which are the same as those of the first and second embodiments, are designated by the same reference characters used for denoting the same constituent elements of the first and second embodiments. Further, the description of such constituent element is omitted herein. Hereunder, constituent elements and features of the third embodiment, which differ from those of the first and second embodiments, are described.

The third embodiment differs from the first and second embodiments in that the air conditioner1of the first embodiment is designed specifically for cooling, and the air conditioner67of the second embodiment is designed specifically for heating, while the air conditioner of the third embodiment is designed for performing both the cooling and the heating. That is, the air conditioner71of this embodiment comprises the exhaust heat recovery unit3, the heat transfer medium pipes5a,5b, the auxiliary boiler7serving as the auxiliary heating device, the absorption chiller9, the refrigerant pipes11a,11b, the indoor unit13, the heat transfer medium temperature sensor15, the refrigerant temperature sensor17, the control portion19, a cooling/heating switch three-way valve73, and bypass pipes75aand75b.

The cooling/heating switch three-way valve73is provided at a part located at the downstream side of a flow of the heat transfer medium from the heat transfer medium pump23of the heat transfer medium pipe5a. The bypass pipe75ais connected to the cooling/heating switch three-way valve73at an end thereof, and also joined to a part located at the downstream side of a flow of the refrigerant from the refrigerant temperature sensor17of the refrigerant pipe11aat the other end thereof. The bypass pipe75bbranches off at an end thereof from the refrigerant pipe11bat a part located at the downstream side of a flow of the refrigerant of the refrigerant pipe11b, and joins to a part located at the upstream side of a flow of the heat transfer medium from a junction portion77between the heat transfer medium pipe5band the non-heat-recovery pipe27. Therefore, during a heating operation, a heat transfer medium flows through the bypass pipe75atoward the indoor unit13. Moreover, the heat transfer medium having discharged heat in the indoor unit13flows through the bypass pipe75btoward the exhaust heat recovery unit3.

The control portion19is electrically connected to the three-way valve25, the auxiliary boiler7, the heat transfer medium temperature sensor15, the heat transfer medium pump23, the cooling/heating switch three-way valve73, pumps (not shown) of the absorption chiller9, cooling fans of a cooling tower (not shown), the refrigerant temperature sensor17, the refrigerant pump33, and a control part (not shown) of the indoor unit13through the wires35.

In the air conditioner71of such a configuration of this embodiment, when there is a request to air-condition and the a cooling operation is selected by using an operation changing switch (not shown), the control portion19switches the cooling/heating switch three-way valve73so that the heat transfer medium and the cooling water circulate through the absorption chiller9, the heat transfer medium pipes5a,5b, and the cooling/heating water pipes11a,11b. Then, the control portion19operates the heat transfer medium pump23provided in the heat transfer medium pipe5a, the refrigerant pump33provided in the refrigerant pipe11b, the cooling fan of the cooling tower (not shown) of the absorption chiller9, and pumps each for circulating cooling water and adsorbent. Thus, the absorption chiller9is driven by heat of the heat transfer medium flowing through the heat transfer medium pipe5a, and performs the cooling of the refrigerant circulating through the refrigerant pipes11a,11b. A cool current of air is sent from the indoor unit13by causing the refrigerant cooled by this absorption chiller9to flow through the refrigerant pipes11a,11b. Thus, the cooling operation is performed.

On the other hand, when there is a request to air-condition and the a heating operation is selected by using an operation changing switch (not shown), the control portion19switches the cooling/heating switch three-way valve73so that the heat transfer medium flowing through the heat transfer medium pipe5ais caused to flow from the refrigerant pipe11ato the indoor unit13through the bypass pipe75a. Then, the control portion19operates the heat transfer medium pump23provided in the heat transfer medium pipe5aand puts the refrigerant pump33provided in the refrigerant pipe11bin to a stopped state. Thus, the heat transfer medium is not supplied to the absorption chiller9and circulates between the exhaust heat recovery unit3and the indoor unit13through the bypass pipes75aand75bfor bypassing the absorption chiller9. A warm current of air is blown out from the indoor unit13by causing the heat transfer medium to flow through the indoor unit13. Thus, the heating operation is performed. Incidentally, the control portion19performs control operations, which are the same as those of the control portions of the first and second embodiment, other than a control process of switching the cooling/heating switch three-way valve73. Further, during a cooling operation, the control operation19of the third embodiment performs a control operation similar to that to be performed in the first embodiment during a cooling operation. Moreover, during a heating operation, the control operation19of the third embodiment performs a control operation similar to that to be performed in the second embodiment during a heating operation.

Thus, in the case of the air conditioner71of the third embodiment, the cooling/heating switch three-way valve73is switch so that the heat transfer medium flows through the bypass pipes75aand75bduring a heating operation. Thus, the heating operation can be performed by supplying the heat transfer medium directly to the indoor unit13. Consequently, both a cooling operation and a heating operation can be performed by a single air conditioner. Moreover, the energy saving capability of the air conditioner can be enhanced.

Further, in the foregoing description of the first, second and third embodiments, it has been described that during a cooling operation, what is called a three-stage three-position or four-position control action is performed, and that during a heating operation, what is called a three-stage four-position or five-position control action is performed. However, a control action according to the invention is not limited thereto. The invention can be applied to various multi-stage multi-position control actions and proportional control actions.

Furthermore, the effect of enhancing the energy-saving capability can be obtained by singly using each of the configurations described in the foregoing description of the first and third embodiments, that is, the configuration, in which an operation of the auxiliary boiler7is controlled according to the temperature of the heat transfer medium during a cooling startup operation and in which an operation of the auxiliary boiler7is controlled according to the temperature of the refrigerant during a cooling stationary operation, the configuration in which the startup of combustion in the auxiliary boiler7or the heating value thereof is performed when a condition, in which the temperature of the refrigerant is equal to or higher than the predetermined temperature, lasts for a predetermined time period during a cooling stationary operation, and the configuration in which the startup of combustion in the auxiliary boiler7or the heating value thereof is performed when a condition, in which the temperature of the heat transfer medium is equal to or lower than the predetermined temperature, lasts for a predetermined time period during a heating stationary operation. Incidentally, when the combination of such configurations is used, the energy-saving capability of the air conditioner can be enhanced still more.

Further, although the three-way valve25and the non-heat-recovery pipe27are used as a heat transfer medium overtemperature protection mechanism for preventing an occurrence of overheat of the heat transfer medium in the first, second and third embodiments, for example, a configuration, in which the exhaust heat recovery unit3may be selectively operated in a heat recovery mode and a non-heat-recovery mode, may be used as that of the heat transfer medium overtemperature protection mechanism. For instance, an exhaust heat recovery unit having a passage switching mechanism adapted to switch a flowing mode between a mode, in which exhaust gas outputted from an exhaust heat source is caused to flow in a passage provided with the heat exchange portion21of the exhaust heat recovery unit3, and another mode, in which the exhaust gas is caused to flow directly into the exhaust gas passage of the exhaust heat recovery unit3without allowing the exhaust gas outputted from the exhaust heat source to flow into the passage provided with the heat exchange portion21, may be used as the exhaust heat recovery unit of such a configuration.

Furthermore, in the foregoing description of the first, second, and third embodiments, an internal-combustion engine is exemplified as the exhaust heat source. The invention, however, may be applied to various air conditioners utilizing exhaust heat outputted from various exhaust heat sources, for example, fuel cells, industrial exhaust heat sources, geothermal sources, and hot springs. Moreover, the exhaust heat is not limited to the heat of exhaust gas. Exhaust heat can be recovered from cooling water for an internal combustion engine. Additionally, the invention is not limited to the air conditioners of the configurations described in the description of the first, second and third embodiments. The invention can be applied to air conditioners of various configurations, as long as such air conditioners are those for performing heating by using exhaust heat, those for performing cooling of refrigerants by absorption chillers driven by exhaust heat, and those provided with features of both of such air conditioners respectively designed specifically for cooling and heating and adapted to perform both the cooling and the heating, and have auxiliary heating devices, such as a heater and a burner.

INDUSTRIAL APPLICABILITY

According to the invention, the energy-saving capability of an air conditioner can be enhanced.