Patent ID: 12235026

DETAILED DESCRIPTION

As the water and space cooling industry strives to create more efficient, greener, more cost-effective heating systems, manufacturers have turned to combining systems to share heat transfer loads. One such combination includes an air-conditioning and water heating system that utilizes a heat pump to both transfer heat to an outside compressor and a water heat exchanger.FIG.1is an example schematic of a prior art combined air conditioning and water heating system100. The system includes a refrigerant circuit105that provides refrigerant to an evaporator coil110, a compressor120, a condenser coil130, and a water heat exchanger140. As indoor airflow160passes across the indoor evaporator coil110, heat is transferred to the refrigerant in the refrigerant circuit105. The low-pressure vaporized refrigerant is then routed to the compressor120, where it is further compressed into a high-pressure vaporized phase. The high pressure vaporized refrigerant can then be routed to a three-way valve150that enables the refrigerant to be sent to either the outdoor condenser coil130or the water heat exchanger140. If sent to the condenser coil130, the heat of the high-pressure vaporized refrigerant is dissipated into outdoor airflow170, which cools the refrigerant to a sub-cooled liquid before it passes back to the indoor evaporator coil110. If the high-pressure vaporized refrigerant from the compressor120is sent to the water heat exchanger140, the heat of the high-pressure vaporized refrigerant is transferred into water stored in water storage145(e.g., a water storage tank), which cools the refrigerant to a sub-cooled liquid before it passes back to the indoor evaporator coil110.

A limitation of the prior-art design shown inFIG.1is the binary nature of the three-way valve150. For example, a typical combination air-conditioning, water-heating system uses an expensive, non-modulating valve that enables the refrigerant to either be routed to the condenser coil130or the water heat exchanger140, but not to both simultaneously. As can be appreciated, this is not an optimal configuration for a combined air conditioning and water heating system100. To illustrate, if the combined system100is set to cooling mode, where the refrigerant is being routed to the outdoor condenser coil130to dissipate heat, the system does not provide heat to the water heat exchanger140. Alternatively, if the combined system100is set to water heating mode, the refrigerant is being routed only to the water heat exchanger140, meaning the heat is not being dissipated to the condenser coil130, thereby degrading the ability to provide air conditioning. Further, because the prior art combined system100is binary, it is more difficult to monitor, modulate, and/or maintain the superheat of the refrigerant that exits the evaporator coil110. For example, if the combined system100is in water heating mode, the temperature of the refrigerant entering the evaporator coil110may be lower than if the combined system100is in air conditioning mode. The prior systems did not provide an option to independently modulate refrigerant flow into the condenser coil130versus the water heat exchanger140to maintain an appropriate superheat (e.g., between 8° F. and 12° F.).

Referring again to the three-way valve150that enables the refrigerant to be sent to either the outdoor condenser coil130or the water heat exchanger140, the placement of the valve within the refrigerant circuit105limits the ability to use a non-binary valve. The three-way valve150is placed serially after the compressor120, such that the refrigerant flowing through the three-way valve150is significantly high-temperature and high-pressure. This is a contributing factor for using a binary valve (e.g., one path or the other), because the valve can be simple yet robust enough to handle the high temperature vaporized refrigerant. To use a non-binary valve would be contraindicated since such a valve would degrade significantly over time and would otherwise be significantly cost prohibitive (based on products available at the time of filing).

The present disclosure provides a solution to the binary nature of prior art combined systems. Instead of placing a three-way valve between the compressor and the water heat exchanger/condenser coil split, the disclosed system utilizes independent electronic expansion valves placed after the condenser coil and the water heat exchanger, respectively, and before the evaporator coil110. The electronic expansion valves can be independently modulated to enable refrigerant flow through the condenser coil and/or evaporator coil. Further, since electronic expansion valves are placed in the refrigerant circuit where the refrigerant is a sub-cooled liquid, the chance of degrading the system over time is substantially lessened, as compared to the prior art combined systems. Various systems and methods are disclosed for combined systems that can independently regulate refrigerant flow using a plurality of independently adjustable electronic expansion valves, and example systems will now be described with reference to the accompanying figures.

FIG.2is a schematic of a combined air conditioning and water heating system200, according to the present disclosure. The combined system200can include a refrigerant circuit205that provides refrigerant to an evaporator coil210, a compressor220, a condenser coil230, and a water heat exchanger240. The water heat exchanger240can be a condenser tube, a brazed plate heat exchanger, and the like. As indoor airflow260passes across the indoor evaporator coil210, heat can be transferred to the refrigerant in the refrigerant circuit205. The low-pressure vaporized refrigerant can then be routed to the compressor220, where it can be further compressed into a high-pressure vaporized phase. The high pressure vaporized refrigerant can then be routed to a valve-free splitter225. For example, instead of having a three-way valve (e.g., three-way valve150inFIG.1), the flow path of the refrigerant circuit205between the compressor220and (a) the water heat exchanger240and (b) the condenser coil230can be valveless and merely include a line split (e.g., splitter225) to either the water heat exchanger240or the condenser coil230. In series after the condenser coil230and before the evaporator coil210, the combined system200can include a first electronic expansion valve250(hereinafter “first EEV250”). In series after the water heat exchanger240and before the evaporator coil210, the combined system200can include a second electronic expansion valve255(hereinafter “second EEV255”).

During normal, full air cooling operation, the combined system200can operate like a standard air conditioning unit with the refrigerant entering the evaporator coil210from the first EEV250. After the evaporator coil(s)210removes heat from the return air stream (evaporates the two-phase refrigerant into a superheated vapor), the compressor220can raise the refrigerant pressure and temperature. The heat from the compressor220can then be rejected in the outside condenser coil230via outdoor airflow270, and condensed to a liquid where it again enters the first EEV250, and the cycle can start again. The second EEV255can be completely closed during this mode so no refrigerant flows through the water heat exchanger240or the second EEV255, although refrigerant charge can be stored in the water heat exchanger240and/or the refrigerant line between the splitter225and the second EEV255.

During full water heating mode, the first EEV250can be completely closed, the refrigerant can flow through the water heat exchanger240(instead of the condenser coil230), and refrigerant can flow through the second EEV255to the evaporator coil210. An outdoor fan can be switched off during full water heating mode to preserve energy since the outdoor condenser coil230is not being utilized in this example.

When the unit is in modulating water heating mode, the controls of the combined system200can be designed such that one of the electronic expansion valves can be opened to a fixed position while the other valve is used to control the superheat at the outlet of the evaporator coil210. For example, when only a small amount of water heating is required, the combined system200can open the second EEV255slightly to an intermediate configuration between fully open and fully closed configurations so that a small amount of refrigerant is metered through. The first EEV250can have a full range of operation necessary to control the superheat at the evaporator coil210outlet. When a large amount of water heating is required (e.g., more than 60%), the operation of the electronic expansion valves can be reversed. In this case the first EEV250can be opened slightly by the controls (e.g., to any of a plurality of intermediate configurations), while the second EEV255can provide a full range of operation necessary to control the superheat at the evaporator outlet. The outdoor fan speed can also be modulated to help control the amount of heat rejection at the outdoor condenser coil230. A unit controller (e.g., controller400) can be programmed to control position of the “fixed” expansion valve during modulating water heating mode. To illustrate using a non-limiting example, if the system is in full cooling mode and first EEV250is maintaining superheat, second EEV255can open to 5% of the prior flow of first EEV250with second EEV250reducing its flow to maintain superheat.

FIG.3is a schematic of a control system for a combined air conditioning and water heating system200, according to the present disclosure. The control system can include a controller400that can output control signals to the first EEV250and/or the second EEV255. The control signals can be transmitted to the respective EEVs in response to the controller400receiving an indication of temperatures at various locations of and around the combined system200. These indications of temperatures, or temperature signals, can be transmitted to the controller400from one or more temperature sensors that can detect the refrigerant temperature within the refrigerant circuit and/or temperature of the heating/cooling of the combined system200, as dictated by demand.

The system can include a first temperature sensor310(i.e., a water temperature sensor) positioned to detect temperature of the water leaving the water storage tank245and/or stored within the water storage tank245. For example, the water storage tank245can include a cool-water inlet320(which brings non-heated water into the tank) and a heated-water outlet330(which supplies heated water to the building upon demand). The first temperature sensor310can be positioned along the heated-water outlet330and/or within the water storage tank245to detect the temperature of the stored water. If the water falls below a predetermined temperature (e.g., around 120° F.), it can be determined that hot water is in demand. In this case, the first temperature sensor310can output a temperature signal (e.g., a water temperature signal) to the controller400indicating hot water is in demand and that the temperature of water stored within the water storage tank245is dropping with use. In response, the controller400can output a control signal to the second EEV255instructing the valve to open at least partially and meter additional heated refrigerant through the water heat exchanger240. As described above, the second EEV255can be metered in this example regardless of the setting of the first EEV250, thus not affecting the air conditioning provided via the condenser coil230/evaporator coil210circuit.

The system can include a second temperature sensor340(i.e., an ambient air temperature sensor) positioned to detect temperature of the ambient air within a space to be cooled via air conditioning. This second temperature sensor340can be similar to or include an internal thermostat used for control of the air conditioning. If the ambient air raises above a predetermined temperature (e.g., 70° F. or whatever the air conditioning may be set to), it can be determined that air conditioning is in demand. In this case, the second temperature sensor340can output a temperature signal (e.g., an ambient air temperature signal) to the controller400indicating air conditioning is in demand. In response, the controller400can output a control signal to the first EEV250instructing the valve to open at least partially and meter additional heated refrigerant through the outdoor condenser coil230. As described above, the first EEV250can be metered in this example regardless of the setting of the second EEV255, thus not affecting the hot water provided via the water heat exchanger240/evaporator coil210circuit.

The system can include a third temperature sensor350(e.g., a refrigerant superheat temperature sensor) positioned to detect the temperature of refrigerant in the refrigerant circuit205as it exits the evaporator coil210. As stated above, the first EEV250and the second EEV255can be metered independently, one being fixed while the other is modulated, or both being modulated simultaneously. That said, the temperature of the refrigerant exiting the evaporator coil210can be modulated by opening and/or closing either of the valves independently. For example, if the temperature of the refrigerant exiting the evaporator coil210falls below a predetermined superheat temperature (e.g., between 8° F. and 12° F.), the third temperature sensor350can output a refrigerant temperature signal to the controller to modulate the superheat. In response, the controller400can output a control signal to one or both of the first EEV250or the second EEV255instructing at least one of the valves to open at least partially and meter additional heated refrigerant through that particular circuit. If hot water is in demand, the control signal can instruct the second EEV255to open more; if air conditioning is in demand, the control signal can instruct the first EEV250to open more; if both air conditioning and hot water are in demand, the control signal can instruct both valves to open more. It is also contemplated that the third temperature sensor350can be positioned at the evaporator coil210.

In addition to or as an alternative to the third temperature sensor350(i.e., a refrigerant superheat temperature sensor) described above, the control system of the combined system200can include a pressure sensor355. The pressure sensor355can be positioned in series between the evaporator coil210and the compressor220. The pressure sensor355can detect a refrigerant pressure exiting the evaporator coil210. If the pressure in the circuit is below a predetermined pressure, this can indicate to the controller400that the superheat is dropping after the evaporator coil210. The pressure sensor355can send a pressure signal to the controller400and, in response the controller400can output a control signal to one or both of the first EEV250or the second EEV255instructing at least one of the valves to open at least partially and meter additional heated refrigerant through that particular circuit. If hot water is in demand, the control signal can instruct the second EEV255to open more; if air conditioning is in demand, the control signal can instruct the first EEV250to open more; if both air conditioning and hot water are in demand, the control signal can instruct both valves to open more. The temperature and pressure sensors described herein can be in wired or wireless communication with the controller400.

Any of the temperature sensors described herein (e.g., first temperature sensor310, second temperature sensor340, and/or third temperature sensor350) can be thermometers, thermocouples, thermistors, and the like. It will be understood that referring to a sensor as a first, second, third, etc. sensor does not mean that any of the sensors are arranged in a particular order or that any of the sensors are required. The combined system200described herein can include any one or all of the sensors. Reference to a first, second, third, etc. merely provides a means to differentiate particular sensors.

FIG.4is a component diagram of an example controller400. The controller400can include a processor410. The processor410can receive signals (e.g., temperature signals from the first temperature sensor310, second temperature sensor340, or third temperature sensor350, or pressure signals from the pressure sensor355) and determine whether the valves (e.g., first EEV250and/or second EEV255) should be adjusted to vary the refrigerant flow into condenser coil230and/or water heat exchanger240. The processor410can include one or more of a microprocessor, microcontroller, digital signal processor, co-processor and/or the like or combinations thereof capable of executing stored instructions and operating upon data. The processor410can constitute a single core or multiple core processor that executes parallel processes simultaneously. For example, the processor410can be a single core processor that is configured with virtual processing technologies. The processor410can use logical processors to simultaneously execute and control multiple processes.

The controller400can include a memory420. The memory420can be in communication with the one or more processors410. The memory420can include instructions, for example a program430or other application, that causes the processor410and/or controller400to complete any of the processes described herein. For example, the memory420can include instructions that cause the controller400and/or processor410to receive input signals (e.g., pressure and/or temperature). The controller400and/or processor410can determine if the water temperature is below a predetermined value, the ambient air is above a predetermined temperature, and/or if the refrigerant leaving the evaporator coil210is below a predetermined pressure/temperature. The controller400and/or processor410can transmit output signals to the expansion valves to adjust refrigerant flow, as described herein. The memory420can include, in some implementations, one or more suitable types of memory (e.g., volatile or non-volatile memory, random access memory (RAM), read only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), magnetic disks, optical disks, floppy disks, hard disks, removable cartridges, flash memory, a redundant array of independent disks (RAID), and the like), for storing files including an operating system, application programs, executable instructions and data.

The controller400can be positioned proximate (e.g., attached to and/or within) the combined system200. Nothing requires the controller400to be positioned near the combined system200, however. That is, the controller400can be located remotely with respect to the combined system200. The controller400can, for example, be integrated into a thermostat or another device (e.g., a computing device, a mobile device, etc.) located somewhere other than the location of the components of the combined system200. The controller400can communicate with the various components of the combined system200or other heating ventilation and air conditioning (HVAC) systems with one or more input/output (I/O) devices440. The I/O device440can include one or more interfaces for receiving signals or input from devices and providing signals or output to one or more devices that allow data to be received and/or transmitted by the controller400. The I/O device440can facilitate wired or wireless connections with any of the components described herein, including the temperature sensors310,340,350or the pressure sensor355.

FIG.5is a flowchart showing an example process500for a controller, for example controller400, according to some examples of the present disclosure. The process500described inFIG.5can be completed by the combined system200shown inFIGS.2and3. Further the system described inFIG.5includes the second temperature sensor340(e.g., air temperature sensor) and the first temperature sensor310(e.g., water temperature sensor) described above.

Process500can begin at step505, where the controller can receive an input signal from an ambient air temperature sensor (e.g., second temperature sensor340). At step510, the controller can determine, based on the data received from the ambient air temperature sensor, if the ambient air temperature is above a predetermined threshold temperature. To illustrate using an example, the predetermined threshold for the ambient air can be 70° F. If the temperature from ambient air temperature sensor reads the air temperature to be 70° or below, the controller400can identify that air conditioning is not in demand.

If the temperature of the ambient air is not greater than the predetermined threshold, process500can take no further action with respect to the air-conditioning circuit (e.g., the condenser coil230/evaporator coil210circuit), but the controller400can continue to receive data from the ambient air temperature sensor. If the temperature of the ambient air is greater than the predetermined threshold, process500can proceed to step515which includes transmitting a first control signal to a first electronic expansion valve (e.g., first EEV250) to at least partially open so as to permit refrigerant flow through the outside condenser coil230.

For combined systems that also independently modulate hot water using the refrigerant circuit, process500can include step520, where the controller400can receive an input signal from a water temperature sensor (e.g., first temperature sensor310). At step525, the controller400can determine, based on the data received from the water temperature sensor, if the water temperature within the water tank (e.g., water storage tank245) is below a predetermined threshold. To illustrate using an example, the predetermined threshold for water stored in or exiting a water storage tank245can be 120° F. If the temperature from water temperature sensor reads the water temperature to be 120° or greater, the controller400can identify that hot water is not in demand. If the temperature is below 120°, then water heating can be determined to be in demand.

If the water temperature is greater than the predetermined threshold, process500can take no further action with respect to the water temperature circuit, but the controller400can continue to receive data from the water temperature sensor. If the water temperature is less than the predetermined threshold, process500can proceed to step530which includes transmitting a second control signal to a second electronic expansion valve (e.g., second EEV255) to at least partially open so as to increase refrigerant flow into a water heat exchanger (e.g., water heat exchanger240). This can provide needed heat, via high pressure, high temperature vaporized refrigerant, to heat the water in the storage tank. Process500can end after step530. Alternatively, other processes can be completed according to the systems and methods described herein. Also, as described above, the systems and methods described herein are able to simultaneously provide heated water and air conditioning, meaning steps505-515and steps520-530can be performed simultaneously.

Certain examples and implementations of the disclosed technology are described above with reference to block and flow diagrams according to examples of the disclosed technology. It will be understood that one or more blocks of the block diagrams and flow diagrams, and combinations of blocks in the block diagrams and flow diagrams, respectively, can be implemented by computer-executable program instructions. Likewise, some blocks of the block diagrams and flow diagrams do not necessarily need to be performed in the order presented, can be repeated, or do not necessarily need to be performed at all, according to some examples or implementations of the disclosed technology. It is also to be understood that the mention of one or more method steps does not preclude the presence of additional method steps or intervening method steps between those steps expressly identified. Additionally, method steps from one process flow diagram or block diagram can be combined with method steps from another process diagram or block diagram. These combinations and/or modifications are contemplated herein.

It should also be noted that, as used in the specification and the appended claims, the singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise. References to a composition containing “a” constituent is intended to include other constituents in addition to the one named.

Ranges may be expressed herein as from “about” or “approximately” or “substantially” one particular value and/or to “about” or “approximately” or “substantially” another particular value. When such a range is expressed, the range includes the one particular value and/or the other particular value (i.e., inclusive endpoints).

Herein, the use of terms such as “having,” “has,” “including,” or “includes” are open-ended and are intended to have the same meaning as terms such as “comprising” or “comprises” and not preclude the presence of other structure, material, or acts. Similarly, though the use of terms such as “can” or “may” are intended to be open-ended and to reflect that structure, material, or acts are not necessary, the failure to use such terms is not intended to reflect that structure, material, or acts are essential. To the extent that structure, material, or acts are presently considered to be essential, they are identified as such.

While the present disclosure has been described in connection with a plurality of exemplary aspects, as illustrated in the various figures and discussed above, it is understood that other similar aspects can be used, or modifications and additions can be made, to the described aspects for performing the same function of the present disclosure without deviating therefrom. For example, in various aspects of the disclosure, methods and compositions were described according to aspects of the presently disclosed subject matter. However, other equivalent methods or composition to these described aspects are also contemplated by the teachings herein. Therefore, the present disclosure should not be limited to any single aspect, but rather construed in breadth and scope in accordance with the appended claims.

The components described hereinafter as making up various elements of the disclosure are intended to be illustrative and not restrictive. Many suitable components that would perform the same or similar functions as the components described herein are intended to be embraced within the scope of the disclosure. Such other components not described herein can include, but are not limited to, for example, similar components that are developed after development of the presently disclosed subject matter. Additionally, the components described herein may apply to any other component within the disclosure. Merely discussing a feature or component in relation to one embodiment does not preclude the feature or component from being used or associated with another embodiment.