Abstract:
The present invention provides a multi-range composite-evaporator type cross-defrosting system for continuous heating operation under an environment temperature range from 20 degree to negative 40 degree Celsius. Said system employs a combination of two defrosting methods under different temperature and humidity conditions; the first defrosting method is used for the outdoor temperature range of 20 degree Celsius to 0 degree Celsius, the second defrosting method is used in the outdoor temperature range of 10 degree Celsius to negative 40 degree Celsius, and a control system will adjust the appropriate threshold for switching between the two defrosting methods.

Description:
RELATED APPLICATION 
   This patent application is a divisional application of and claims priority from U.S. application Ser. No. 11/311,085, filed Dec. 20, 2005 now U.S. Pat. No. 7,614,249. 

   FIELD OF THE INVENTION 
   The present invention relates to a multi-range composite-evaporator type cross-defrosting system, more particularly to a heating or air-conditioning system that is capable of continuous operation under the outdoor temperature range of 20 degree Celsius to negative 40 degree Celsius. 
   The present invention can be applied on the fields of residential, agriculture, and industrial; more particularly, the present invention can be used on heating and air-conditioning purpose. 
   BACKGROUND OF THE INVENTION 
   The present invention is a divisional application of the patent application Ser. No. 11/311,085 filed on Dec. 20, 2005, entitled “Multi-range cross defrosting heat pump system and humidity control system.” 
   In general, current heat pump system has very limited range of working temperatures due to the limitation and the operation efficiency of the compressor; however, in many circumstances, the environment temperature may vary from negative 40 degree to 20 degree Celsius, therefore it is main objective of the present invention to provide a multi-range cross defrosting heat pump capable of operating under a wide range of working environment temperature at high efficiency. 
   SUMMARY OF THE INVENTION 
   1. It is a primary object of the present invention to provide a multi-range composite-evaporator type cross-defrosting system capable of continuous operation under various ranges of temperature. 
   2. It is a second object of the present invention to provide a multi-range composite-evaporator type cross-defrosting system capable of continuous operation during the defrosting process. 
   3. It is another object of the present invention to provide an efficient defrosting control method of the multi-range composite-evaporator type cross-defrosting system, which is capable of cross-defrosting with the heat energy absorbed from the outdoor-air-flow and the heat energy generated from the compressor. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1A  to  FIG. 1E  are the illustrative diagrams of the composite-evaporator type cross-defrosting system constructed of refrigerant-defrost type composite-evaporators; the control logics of said system is provided in Table.1 as a reference. 
       FIG. 1A  is an operation scheme of the first embodiment, in which all the composite-evaporators are operating with evaporation process. 
       FIG. 1B  and  FIG. 1C  are the operation schemes of the first defrosting method of the first embodiment, which is also called as the cross-air defrosting process. 
       FIG. 1D  and  FIG. 1E  are the operation schemes of the second defrosting method of the first embodiment, which is also called as the cross-refrigeration defrosting process. 
       FIG. 1G  is an alternative construction scheme of the first embodiment with four composite-evaporators. 
   

   Table.1 demonstrates the control scheme of the first embodiment in each process of cross-refrigerant defrosting process. 
   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Now referring to  FIG. 1A  to  FIG. 1E  and Table.1 for the first embodiment, which is the composite-evaporator type cross-defrosting system constructed of refrigerant-defrost type composite-evaporators; the control logics of said system is provided in Table.1 as a reference. 
   The first embodiment also operates with a control system that changes the defrosting methods according to the outdoor temperature and humidity; when the outdoor temperature is in the range of 20 degree Celsius to 0 degree Celsius, the control system can apply the first defrosting method, which is also called as the cross-air defrosting process; when the outdoor temperature is in the range of 10 degree Celsius to negative 40 degree Celsius, the control system can apply the second defrosting method, which is also called as the cross-refrigeration defrosting process; the threshold at which the control system switches between the cross-air defrosting process and the cross-refrigeration defrosting process can be adjust at any point between 10 degree Celsius to 0 degree Celsius. 
   The composite-evaporator type cross-defrosting system comprising the following basic components: main compressor  101 , main condenser  102 , first composite-evaporator  103 , second composite-evaporator  104 , main expansion valve  107 , first control valve  112 , second control valve  111 , first defrost-flow valve  114 , second defrost-flow valve  113 , first expansion valve  121 , second expansion valve  122 , first venting fan (not shown), second venting fan (not shown), outdoor temperature sensor (not shown), separate heat insulation means for each of said composite-evaporators, a control system for selecting and commencing the defrost-cycles of the cross-air defrosting process and the cross-refrigeration defrosting process. 
   The first composite-evaporator  103  is constructed of one set of evaporation coil and one set of defrost-condensation coil  105 , said evaporation coil and said defrost-condensation coil  105  will share the radiator fins so that the heat energy can be transferred from said defrost-condensation coil to said evaporation coil during the cross-refrigeration defrosting process of the first composite-evaporator  103 ; the defrost-condensation coil  105  of the first composite-evaporator  103  will be referred as the first defrost-condenser  105 . 
   The second composite-evaporator  104  is constructed of one set of evaporation coil and one set of defrost-condensation coil  106 , said evaporation coil and said defrost-condensation coil  106  will share the radiator fins so that the heat energy can be transferred from said defrost-condensation coil to said evaporation coil during the cross-refrigeration defrosting process of the second composite-evaporator  104 ; the defrost-condensation coil  106  of the first composite-evaporator  104  will be referred as the second defrost-condenser  106 . 
   Now referring to  FIG. 1A  for the full capacity heating operation when both the first composite-evaporator  103  and second composite-evaporator  104  are operating with the evaporation process; the evaporation coil of the first composite-evaporator  103  and the evaporation coil of the second composite-evaporator  104  are enabled by opening the first control valve  112  and second control valve  111 ; the first defrost-condenser  105  and the second defrost-condenser  106  are disabled by shutting the first defrost-flow valve  114  and the second defrost-flow valve  113 ; the first venting fan and the second venting fan will be operating to provide the outdoor-air into the heat insulated space of the first composite evaporator  103  and the heat insulated space of the second composite-evaporator  104 ; the main compressor  101  and the main condenser  102  will be operating with the pressurization process and the condensation process respectively to provide the heat energy for the air-conditioning or heating. 
   Now referring to  FIG. 1B  and  FIG. 1C  for the cross-air defrosting process of the first embodiment; the control system can employ said cross-air defrosting process when the outdoor temperature is between 20 degree Celsius and 0 degree Celsius; during the defrost-cycle of the cross-air defrosting process, the control system will defrost each evaporator with a defrost-cycle as follows; the first composite-evaporator  103  defrosts with the cross-air defrosting process for 5 minute (this duration is only for demonstration purpose and not to be considered as limitation or element) as shown in  FIG. 1B , and next the second composite-evaporator  104  defrosts with the cross-air defrosting process for 5 minute as shown in  FIG. 1C , and next the first composite-evaporator  103  and the second composite-evaporator  104  will resume the evaporation process as shown in  FIG. 1A  or repeat the defrost-cycle if the weather condition requires continuous defrost-cycle. 
   As shown in  FIG. 1B , the first composite-evaporator  103  is defrosting with the cross-air defrosting process; the evaporation coil of the first composite-evaporator  103  is disabled, and the outdoor-air will be drawn into the heat insulated space of the first composite-evaporator  103  to melt the accumulated frost on the first composite-evaporator  103 ; the second composite-evaporator  104  will operate with the evaporation process to provide the evaporated refrigerant to the main compressor  101 ; the main compressor  101  and the main condenser  102  will continue the pressurization process and the condensation process respectively for the air-conditioning; the first defrost-condenser  105  and the second defrost-condenser  105  will remain disabled during the defrost cycle of the cross-air defrosting process. 
   As shown in  FIG. 1C , the second composite-evaporator  104  is defrosting with the cross-air defrosting process; the evaporation coil of the second composite-evaporator  104  is disabled, and the outdoor-air will be drawn into the heat insulated space of the second composite-evaporator  104  to melt the accumulated frost on the second composite-evaporator  104 ; the first composite-evaporator  103  will operate with the evaporation process to provide the evaporated refrigerant to the main compressor  101 ; the main compressor  101  and the main condenser  102  will continue the pressurization process and the condensation process respectively for the air-conditioning; the first defrost-condenser  105  and the second defrost-condenser  106  will remain disabled during the defrost cycle of the cross-air defrosting process. 
   Now referring to  FIG. 1D  and  FIG. 1E  for the second defrosting method (the continuous defrost-cycle of the cross-refrigeration defrosting process); when the outdoor temperature drops below the threshold for initiating the cross-refrigeration defrosting process, the control system will commence a defrost-cycle as follows; the first composite-evaporator  103  and the second composite-evaporator  104  will operate with the evaporation process as shown in  FIG. 1A  for 10 minute, and next the first composite-evaporator  103  defrosts with the cross-refrigeration defrosting process as shown in  FIG. 1D  for 2 minute (this time duration is only for demonstration purpose and not to be a limitation or element), and next the second composite-evaporator  104  defrosts with the cross-refrigeration defrosting process as shown in  FIG. 1E  for 2 minute, and next the control system will repeat the defrost-cycle until further change in the outdoor environment is detected. 
   The basic concept of the cross-refrigeration defrosting process is to distribute a controlled flow of the pressurized refrigerant into the defrost-condensation coil of the composite-evaporator that is defrosting, so that the accumulated frost on said composite-evaporator will melt by the heat energy transferred from its associated defrost-condenser, therefore, the time necessary for the defrosting process will be greatly shortened; the other evaporator of the system will continue the evaporation process with its associated evaporation coil, the main compressor and the main condenser will also continue their operation to generate the heat energy for the air-conditioning. The defrost-cycle of the cross-refrigeration defrosting process requires each evaporator to alternate its operation at a time interval, and the control schemes of each process are provide in  FIG. 1D  and  FIG. 1E . 
   As shown in  FIG. 1D , the first composite-evaporator  103  is defrosting with the cross-refrigeration defrosting process; the first composite-evaporator  103  will disable its associated evaporation coil and enable the first defrost-condenser  105  by opening the first defrost-flow valve  114 ; a controlled flow of pressurized refrigerant is distributed from the main compressor  101  to the first defrost-condenser  105 , and said flow of pressurized refrigerant will release heat energy in the first defrost-condenser  105  to transfer a heat current to the evaporation coil of the first composite-evaporator  103 , and next the first defrost-condenser  105  will transfer the refrigerant therein to the evaporation coil of the second composite-evaporator  104  via the first expansion valve  121 ; the first venting fan will decrease speed or stop the air-flow from outdoor, thereby conserving the heat air inside the heat insulated space of the first composite-evaporator  103 , thus creating a hot environment; the second composite-evaporator  104  will receive the refrigerant-flow from the main expansion valve  107  and the refrigerant-flow from the first expansion valve  121 ; in other words, the main condenser  102  and the first defrost-condenser  105  will be condensing refrigerant to generate heat energy for the air-conditioning and the cross-refrigeration defrosting process respectively, while the second composite-evaporator  104  will be operating with the evaporation process by absorbing the heat from the outdoor-air; the second defrost-condenser  106  is disabled by shutting the second defrost-flow valve  113 . 
   As shown in  FIG. 1E , the second composite-evaporator  104  is defrosting with the cross-refrigeration defrosting process; the second composite-evaporator  104  will disable its associated evaporation coil and enable the second defrost-condenser  106  by opening the second defrost-flow valve  113 ; a controlled flow of pressurized refrigerant is distributed from the main compressor  101  to the second defrost-condenser  106 , and said flow of pressurized refrigerant will release heat energy in the second defrost-condenser  106  to transfer a heat current to the evaporation coil of the second composite-evaporator  104 , and next the second defrost-condenser  106  will transfer the refrigerant therein to the evaporation coil of the first composite-evaporator  103  via the second expansion valve  122 ; the second venting fan will decrease speed or stop the air flow from outdoor, thereby conserving the heat air inside the heat insulated space of the second composite-evaporator  104 , thus creating a hot environment; the first composite-evaporator  103  will receive the refrigerant-flow from the main expansion valve  107  and the refrigerant-flow from the second expansion valve  122 ; in other words, the main condenser  102  and the second defrost-condenser  106  will be condensing refrigerant to generate heat energy for the air-conditioning and the cross-refrigeration defrosting process respectively, while the first composite-evaporator  103  will be operating with the evaporation process by absorbing the heat from the outdoor-air; the first defrost-condenser  105  is disabled by shutting the first defrost-flow valve  114 . 
   The first embodiment of the present invention can be further extended with additional composite evaporators, and the control system can adjust accordingly to the basic concept of the present invention; when one of the evaporators is frosted and requires to defrost with the cross-refrigeration defrosting process, said frosted composite-evaporator will disable its associated evaporation coil and enable its associated defrost-condenser to initiate a controlled flow of pressurized refrigerant from the main compressor, said defrost condenser will conduct a heat current through its radiator fins to said frosted composite-evaporator, and the heat insulated space of said frosted evaporator will control the operation speed of its associated venting fan to conserve the heat air therein, meanwhile, all other composite-evaporators can continue the evaporation process with their associated evaporation coils to absorb heat energy from the outdoor-air, the main compressor and the main condenser will continue their operation for the air-conditioning or heating; the control system will also operate with a continuous defrost-cycle, wherein each composite-evaporator will take turns to operate with the cross-refrigeration defrosting process; an example of the defrost cycle is demonstrated as follows, all composite-evaporators operate with the evaporation process for 10 minute, and next the first composite-evaporator defrosts for 2 minute, next the second composite-evaporator defrosts for 2 minute, and next the third composite-evaporator defrosts for 2 minute, and next the fourth composite-evaporator defrosts for 2 minute, and next the control system repeats the defrost-cycle or adjust its operation if further change in the weather condition is detected. A construction scheme is provided in  FIG. 1G  for an alternative construction of the first embodiment consisting of four composite-evaporators, wherein the third composite-evaporator  153  has one set of evaporation coil and one set of defrost-condensation coil  155 , the fourth composite-evaporator  172  has one set of evaporation coil and one set of defrost-condensation coil  156 , the third control valve  162  will disable the refrigerant passage to the evaporation coil of the third composite-evaporator  153  during the cross-air defrosting process and the cross-refrigerant defrosting process of the third composite-evaporator  153 , the fourth control valve  161  will disable the refrigerant passage to the evaporation coil of the fourth composite-evaporator  154 ; the third defrost-flow valve  164  will enable a refrigerant passage to provide a flow of pressurized refrigerant to the defrost-condensation coil  155  of the third composite-evaporator during the cross-refrigerant defrosting process of the third composite-evaporator  153 ; the fourth defrost-flow valve  163  will enable a refrigerant passage to provide a flow of pressurized refrigerant to the defrost-condensation coil  156  of the fourth composite-evaporator  154  during the cross-refrigerant defrosting process of the fourth composite-evaporator  154 . 
   For easier maintenance and cost reduction, most control valves can be combined into one single rotary valve or other multi-port control valve means, for instance, the first defrost-flow valve  114  and the second defrost-flow valve  113  can be constructed with one multi-port control valve of the identical functionality, and the first control valve  112  and second control valve  111  can also be constructed with one multi-port control valve of the identical functionality. 
   The control system can further employ the sensor means for the progress of the defrosting process to detect if a composite-evaporator has melted all the frost thereon, if the frost is completely melted, the control system can be reset to the next step of the defrost-cycle; said sensor means can be a pressure or temperature sensor in the composite evaporator. 
   It should be understood that the threshold temperatures for initiating each defrosting method are different for other regions in the world, where the humidity and frosting condition are the main factor deciding which defrosting method to apply at different temperature range. 
   
     
       
             
           
             
             
             
             
             
           
         
             
               TABLE 1 
             
           
           
             
                 
             
             
               Part.1 Control logics of the second embodiment 
             
           
        
         
             
                 
                 
               Full capacity heating 
               Cross-air defrosting process of 
               Cross-air defrosting process of 
             
             
               Label 
               Component Name 
               operation 
               first composite evaporator 
               Second composite evaporator 
             
             
                 
             
             
               102 
               Main condenser 
               Condensation Process 
               Condensation Process 
               Condensation Process 
             
             
               103 
               First composite- 
               Evaporation Process 
               Defrosting with 
               Evaporation Process 
             
             
                 
               evaporator 
               (evaporation coil en- 
               outdoor-air 
               (evaporation coil enabled) 
             
             
                 
                 
               abled) 
               (evaporation coil disabled) 
                 
             
             
               104 
               Second composite- 
               Evaporation Process 
               Evaporation Process 
               Defrosting with 
             
             
                 
               evaporator 
               (evaporation coil en- 
               (evaporation coil enabled) 
               outdoor-air 
             
             
                 
                 
               abled) 
                 
               (evaporation coil disabled) 
             
             
               114 
               First defrost-flow valve 
               Closed 
               Closed 
               Closed 
             
             
               113 
               Second defrost-flow 
               Closed 
               Closed 
               Closed 
             
             
                 
               valve 
             
             
               112 
               First control valve 
               Open 
               Closed 
               Open 
             
             
               105 
               First defrost-condenser 
               No refrigerant-flow 
               No refrigerant-flow 
               No refrigerant-flow 
             
             
               111 
               Second control valve 
               Open 
               Open 
               Closed 
             
             
               106 
               Second defrost-condenser 
               No refrigerant-flow 
               No refrigerant-flow 
               No refrigerant-flow 
             
             
                 
               First venting fan 
               Full speed 
               Full speed 
               Full speed 
             
             
                 
               Second venting fan 
               Full speed 
               Full speed 
               Full speed 
             
             
                 
             
           
        
       
     
   
   
     
       
             
           
             
             
             
             
             
           
         
             
               TABLE 1 
             
           
           
             
                 
             
             
               Part.2 Control logics of the second embodiment 
             
           
        
         
             
                 
                 
                 
               Cross-refrigerant 
               Cross-refrigerant 
             
             
                 
                 
                 
               defrosting process 
               defrosting process 
             
             
                 
                 
               Full capacity heating 
               of first 
               of second 
             
             
               Label 
               Component Name 
               operation 
               composite evaporator 
               composite evaporator 
             
             
                 
             
             
               102 
               Main condenser 
               Condensation Process 
               Condensation Process 
               Condensation Process 
             
             
               103 
               First composite-evaporator 
               Evaporation Process 
               Defrosting by 
               Evaporation Process 
             
             
                 
                 
               (evaporation coil en- 
               first defrost-condenser 
               (evaporation coil enabled) 
             
             
                 
                 
               abled) 
               (evaporation coil dis- 
             
             
                 
                 
                 
               abled) 
                 
             
             
               104 
               Second composite-evaporator 
               Evaporation Process 
               Evaporation Process 
               Defrosting by 
             
             
                 
                 
               (evaporation coil en- 
               (evaporation coil en- 
               second defrost-condenser 
             
             
                 
                 
               abled) 
               abled) 
               (evaporation coil disabled) 
             
             
               114 
               First defrost-flow valve 
               Closed 
               Open 
               Closed 
             
             
               113 
               Second defrost-flow valve 
               Closed 
               Closed 
               Open 
             
             
               112 
               First control valve 
               Open 
               Closed 
               Open 
             
             
               105 
               First defrost-condenser 
               No refrigerant-flow 
               Condensation Process 
               No refrigerant-flow 
             
             
               111 
               Second control valve 
               Open 
               Open 
               Closed 
             
             
               106 
               Second defrost-condenser 
               No refrigerant-flow 
               No refrigerant flow 
               Condensation Process 
             
             
                 
               First venting fan 
               Full speed 
               Decreasing speed or stop 
               Full speed 
             
             
                 
                 
                 
               to conserve heat 
                 
             
             
                 
               Second venting fan 
               Full speed 
               Full speed 
               Decreasing speed or stop 
             
             
                 
                 
                 
                 
               to conserve heat