Cross-reverse type air-conditioning system

Abstract

The present invention provides an air-conditioning system capable of continuous heating operation over an outdoor temperature range of 20 degree to negative 40 degree Celsius. The present invention utilizes at least two sets of the evaporators capable of cross-reverse refrigerant circulation and cross-air defrosting process, which alternately generates the heat energy required for the defrosting process and the air-conditioning, and said air-conditioning system can apply a combination of the two defrost methods to raise overall heating efficiency.

Description

FIELD OF THE INVENTION

The present invention relates to a forced-air-defrost type air-conditioning system, more particularly to a cross-reverse type air-conditioning system capable of the cross-reverse defrosting process and the cross-air defrosting process.

The present invention can be applied on residential, agriculture, and industrial purposes.

BACKGROUND OF THE INVENTION

The present invention is a divisional application of the patent application No. 20070137238 filed on Dec. 20, 2005, entitled “Multi-range cross defrosting heat pump system and humidity control system.”

Current available heat pump requires different types of compressors for different range of working environment temperature; therefore, the user may need to install multiple air-conditioning systems such as a combination of a heat pump and a gas heater for different range of working temperature. One of the reasons is the low efficiency of the heat pump under low working temperature; another reason is the need for interrupting operation due to the frost conditions on evaporators.

The current defrosting methods such as electrical defrost system and reverse-circulation defrost system require the heat pump to stop operation while defrosting. Therefore, it is one objective of the present invention to provide an air-condition heat pump capable of uninterrupted operation during system defrosting process.

Another objective of the present invention is to provide the most efficient control methods for cross defrosting heat pump system under different temperature and humidity conditions; most heat pumps require the heat energy from other source to maintain the heating efficiency while the present invention defrosts with the heat energy absorbed from the environment and the heat energy generated by the compressor.

Current compressors have very low efficiency under low temperature range, the current two-stage compressors utilize two compression strokes to increase system efficiency, however, the current two-stage compressors can not operate under different temperature range, in other words, the two-stage compressor can not operate under the environment that does not require pressure boosting; therefore it is another objective of the present invention to provide a multi-stage pressure boosting heat pump system capable of adjusting the level of pressure boosting in order to operate under a wide range of working environment temperature.

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 the primary objective of the present invention to provide a cross-reverse type air-conditioning system capable of defrosting with cross-reverse refrigerant circulation and cross-air defrosting process.

2. It is the secondary objective of the present invention to provide the control method for the cross-reverse type air-conditioning system to prevent the evaporators from malfunctioning.

3. It is the third objective of the present invention to provide a cross-reverse type air-conditioning system capable for frost-prevention over an outdoor temperature range 20 degree Celsius to negative 40 degree Celsius.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A to FIG. 1I are the illustrative diagrams of the cross-reverse type air-conditioning system. The control logic table of cross-reverse type air-conditioning system is provided in Table. 1 as a reference to FIG. 1A to FIG. 1E.

FIG. 1F is an exemplary construction scheme of the cross-reverse type air-conditioning system utilizing rotary valves.

FIG. 1H and FIG. 1J are construction schemes of the cross-reverse type air-conditioning system utilizing more than two evaporators.

FIG. 1I is another possible modified construction scheme based on the cross-reverse type air-conditioning system.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The first embodiment of present invention is shown in FIG. 1A to FIG. 1F and the table 1 is used as a reference to understand the control method of the present invention. As shown in the table 1, the present invention includes a combination of the two defrosting methods, the first defrosting method can be applied to the operation environment where the outdoor temperature is from 20 degree Celsius to 0 degree Celsius, the second defrosting method can be applied to the operation environment where the outdoor temperature is from 10 degree to negative 40 degree Celsius; the threshold of switching the system from the first defrosting method to the second defrosting method can be adjusted according to the operating condition. However, for the ease of comprehension, the following embodiments will be explained with a threshold of 5 degree Celsius for the system to switch from the first defrosting method to the second defrosting method.

Now referring to FIG. 1A and the table 1, the cross-reverse type air-conditioning system comprising the following basic components: main compressor 101, main condenser 102, first evaporator 121, second evaporator 122, main expansion valve 103, first upper-flow control valve 131, second upper-flow control valve 132, first lower-flow control valve 171, second lower-flow control valve 172, first reverse-flow control valve 151, second reverse-flow control valve 152, first expansion valve 141, second expansion valve 142, first one-way valve 161, second one-way valve 162, first venting fan (not shown), second venting fan (not shown), separate insulation means (not shown) for each evaporator.

Now referring to FIG. 1A for the full capacity heating operation of the cross-reverse type air-conditioning system; the refrigerant-flow of the first evaporator 121 and the refrigerant-flow of the second evaporator 122 are enabled, so that both the first evaporator 121 and the second evaporator 122 are absorbing the heat from the outdoor-air-flow for the evaporating process therein; the first upper-flow control valve 131 and the first lower-flow control valve 171 are open to enable the refrigerant-flow of the first evaporator 121; the second upper-flow control valve 132 and the second lower-flow control valve 172 are open to enable the refrigerant flow of the second evaporator 122; all the control valves for cross-reverse refrigerant circulation are shut to disable the hot refrigerant flow from the main compressor 101 to the first evaporator 121 and the second evaporator 122; the first reverse-flow control valve 151 and second reverse-flow control valve 152 are shut. The refrigerant in said two evaporators absorbs heat from the outdoor-air-flow and next, the evaporated refrigerant is pressurized in main compressor 101, and next the main condenser 102 releases the heat energy for the air-conditioning.

Now referring to FIG. 1B and FIG. 1C for the first defrosting method of the cross-reverse type air-conditioning system, said first defrosting method can also be called as cross-air defrosting process; when the first defrosting method is employed, said system operates with a defrost-cycle which is depending on the outdoor temperature and the humidity. An exemplary defrost-cycle is provided as follow; the first evaporator 121 and the second evaporator 122 operate with the evaporation process for 5 minutes as shown in FIG. 1A, and next the first evaporator 121 defrosts with the first defrosting method as shown in FIG. 1B, and next the second evaporator 122 defrosts with the first defrosting method as shown in FIG. 1C, and then said system repeats the defrost-cycle until further change in the outdoor temperature is detected.

As shown in FIG. 1B, the first evaporator is defrosting with the first defrosting method; the refrigerant flow of the first evaporator 121 is disabled by the first upper-flow control valve 131 and first lower-flow control valve 171, the first venting fan will operate at full speed to draw the outdoor air through the first evaporator 121 to melt the frost thereon; the second evaporator 122 will continue the evaporation process to provide a sufficient refrigerant flow to the main compressor 101, the main condenser 102 will continue to generate the heat energy required for the air-conditioning.

As shown in FIG. 1C, the second evaporator is defrosting with the first defrosting method, the refrigerant flow of the second evaporator 122 is disabled by the second upper-flow control valve 132 and the second lower-flow control valve 172, the second venting fan will operate at full speed to draw the outdoor air through the second evaporator 122 to melt the frost thereon; the first evaporator 121 will continue the evaporation process to provide a sufficient refrigerant flow to the main compressor 101, the main condenser 102 will continue to generate the heat energy required for the air-conditioning.

When the outdoor temperature reaches the threshold, at which the first defrosting method cannot provide enough heat energy with the outdoor air, the system can switch to the second defrosting method as shown in FIG. 1D and FIG. 1E, and said second defrosting method is also called as the cross-reverse defrosting process. The cross-reverse defrosting process also operate in a similar defrost-cycle as the first defrosting method, an exemplary defrost-cycle is provided as follows; the first evaporator 121 and the second evaporator 122 together operate to generate heat energy as shown in FIG. 1A for 10 minute, and next the first evaporator 121 defrosts with the cross-reverse defrosting process as shown in FIG. 1D for 3 minute, and next the second evaporator 122 defrosts with the cross-reverse defrosting process as shown in FIG. 1E for 3 minute, and next the system repeats the cycle until further change in the outdoor environment is detected.

As shown in FIG. 1D, the first evaporator 121 is defrosting with the second defrosting method, the cross-reverse defrosting process; the first evaporator 121 will stop the evaporation process and disable the refrigerant-flow from the main expansion valve 103 by shutting the first upper-flow control valve 131 and first lower-flow control valve 171. The cross-reverse refrigerant circulation will be initiated by opening the first reverse-flow control valve 151, providing a refrigerant passage from the main compressor 101 to the first evaporator 121, so the pressurized refrigerant from the discharge port of the main compressor 101 will now flow to the main condenser 102 and the first evaporator 121; said pressurized refrigerant will condense in the first evaporator 121 to heat up and melt the accumulated ice on the first evaporator 121, and said refrigerant-flow of the first evaporator 121 will exit through the first expansion valve 141 and the first one-way valve into the second evaporator 122; the second evaporator 122 will now receive both the refrigerant-flow from the main expansion valve 103 and the refrigerant-flow from the first one-way valve 161; in other words, the main condenser 102 and the first evaporator 121 will be condensing refrigerant to generate heat energy for the air-conditioning and the cross-reverse defrosting process respectively, while the second evaporator 122 will be evaporating the refrigerant by absorbing the heat from the outdoor-air-flow; the first venting fan will stop or spin slowly to conserve the heat energy in the first evaporator 121, the second venting fan will be operating at full speed to provide a sufficient flow of the outdoor air for the evaporating process of the second evaporator 122.

As shown in FIG. 1E, the second evaporator 122 is defrosting with the second defrosting method, the cross-reverse defrosting process; the second evaporator 122 will stop the evaporation process and disable the refrigerant-flow from the main expansion valve 103 by shutting the second upper-flow control valve 132 and second lower-flow control valve 172. The cross-reverse refrigerant circulation will be initiated by opening the second reverse-flow control valve 152, providing a refrigerant passage from the main compressor 101 to the second evaporator 122, so the pressurized refrigerant from the discharge port of the main compressor 101 will now flow to the main condenser 102 and the second evaporator 122; said pressurized refrigerant will condense in the second evaporator 122 to heat up and melt the accumulated ice on the second evaporator 122, and said refrigerant-flow of the second evaporator 122 will exit through the second expansion valve 142 and the second one-way valve 162 into the first evaporator 121; the first evaporator 121 will now receive both the refrigerant-flow from the main expansion valve 103 and the refrigerant-flow from the second one-way valve 162; in other words, the main condenser 102 and the second evaporator 122 will be condensing refrigerant to generate heat energy for the air-conditioning and the cross-reverse defrosting process respectively, while the first evaporator 121 will be evaporating refrigerant by absorbing the heat from the outdoor-air-flow; the first venting fan will stop or spin slow to conserve the heat energy in the second evaporator 122, the first venting fan will be operating at full speed to provide a sufficient flow of the outdoor air for the evaporating process of the first evaporator 121.

Under the operating condition where the outdoor temperature is below 0 degree Celsius, the cross-reverse type air-conditioning system has to continue the cross-reverse refrigerant circulation at an appropriate time interval to prevent any of the evaporators from being completely frosted; in order to maximize the efficiency of heat absorption, the cross-reverse defrosting air-condition system can employed more than 2 evaporators for reducing the time required for each defrosting process intervals; in other words, for a cross-reverse type air-conditioning system with three evaporators, the first evaporator will defrost with the cross-reverse defrosting process while the second evaporator and the third evaporator are continuing the evaporating process for a time interval, and next the second evaporator will defrost with the cross-reverse defrosting process while the first evaporator and the third evaporator are continuing the evaporating process for a time interval, and next the third evaporator will defrost with the cross-reverse defrosting process while the first evaporator and the second evaporator are continuing the evaporating process for a time interval. Various time schedule can be used to maximize the heating efficiency of the present invention, however, it should be noted that the time interval for switching between the defrosting process of each evaporator should not be overestimated to cause all the evaporators being heavily frosted at the same time because the present invention is mostly used in the cold region, and the malfunction of the indoor heating can be fatal for the residential use in the crucial weather.

A construction scheme is shown in FIG. 1H for the cross-reverse type air-conditioning system with more than two evaporators. When each evaporator is defrosting with first defrosting method, that evaporator stops its refrigerant-flow by shutting its associated upper-flow control valve and lower-flow control valve, and its associated venting fan is operating at full speed to defrost with the outdoor-air-flow. A construction scheme is shown in FIG. 1.J for the cross-reverse type air-conditioning system with four evaporators and the cross-reverse refrigerant circuit.

When each evaporator is defrosting with second defrosting method, its associated upper-flow control valve and lower-flow control valve are shut, and its reverse-flow control valve is open to provide direct passage between that evaporator and discharge port of the main compressor; its associated venting fan will stop or spin slowly to conserve the heat within the heat insulated space of that evaporator. The second defrosting method utilizes the heat absorbed from the other evaporators and the heat generated from the main compressor to melt the ice on the evaporator that is defrosting.

An exemplary defrost-cycle is provide for the cross-reverse type air-conditioning system with 3 evaporators; all evaporators are evaporating refrigerant at full capacity for 5 minutes, then the first evaporator defrosts for 5 minute, and next the second evaporator defrosts for 5 minute, and next the third evaporator defrosts for 5 minutes, thus completed one cycle and the system will detect if the outdoor temperature has raised or decreased over the threshold for switching to another defrost method.

For easier maintenance, most control valves can be combined into one single rotary valve or other multi-port control valve means. A control valve construction scheme of the cross-reverse type air-conditioning system with rotary valves is provided in FIG. 1F, wherein first reverse-flow control valve 151 and first upper-flow control valve 131 are replaced with first rotary upper-flow control valve 131 capable of same functions, first lower-flow control valve 171 and first one-way valve 161 can be replaced with first rotary lower-flow control valve 171 capable of same functions. Another construction scheme is provided in FIG. 1I, wherein the pressurized refrigerant enters the defrosting evaporator from the discharge port of the defrosting evaporator during the cross-reverse defrosting process. Many other construction schemes and control valve means are possible to perform the same task based on the present invention and should be considered within the scope of the present invention.

The system can also further employ a defrosting process sensor means to detect if the evaporator has melted all the ice thereon, if no further defrosting is required, the system will reset to the next step of the defrost-cycle. The defrosting process sensor means can be a refrigerant pressure or refrigerant temperature sensor.

TABLE 1
Control logics of Cross-reverse type air-conditioning system
		Full capacity	Cross-air defrosting	Cross-air defrosting	Cross-reverse defrosting	Cross-reverse defrosting
		Heating	process of	process of	process of	process of
Label	Component Name	Operation	First evaporator	Second evaporator	First evaporator	Second evaporator
102	Main condenser	Condensation	Condensation	Condensation	Condensation	Condensation
		Process	Process	Process	Process	Process
121	First evaporator	Evaporation	Defrosting with	Evaporation	Cross Reverse	Evaporation
		Process	Outdoor-air-flow	Process	Defrosting	Process
			(no refrigerant flow)
122	Second evaporator	Evaporation	Evaporation	Defrosting with	Evaporation	Cross Reverse
		Process	Process	Outdoor-air-flow	Process	Defrosting
				(no refrigerant flow)
151	First reverse-flow	Closed	Closed	Closed	Open	Closed
	control valve
152	Second reverse-flow	Closed	Closed	Closed	Closed	Open
	control valve
131	First upper-flow	Open	Closed	Open	Closed	Open
	control valve
171	First lower-flow	Open	NA	Open	Closed	Open
	control valve		(preferably closed)
132	Second upper-flow	Open	Open	Closed	Open	Closed
	control valve
172	Second lower-flow	Open	Open	NA	Open	Closed
	control valve			(preferably closed)
	First venting fan	Full speed	Full speed	Full speed	Decreasing speed	Full speed
	Second venting fan	Full speed	Full speed	Full speed	Full speed	Decreasing speed

Claims

1. A cross-reverse type air-conditioning system comprising: a) a main refrigeration circuit for the air-conditioning, said main refrigeration circuit consisting a main compressor for pressurizing refrigerant, a main condenser for condensing refrigerant and releasing heat, at least two evaporators for evaporating refrigerant and absorbing heat energy, a main expansion valve for regulating the refrigerant pressure difference between said main condenser and said two evaporators;b) each of said two evaporators including flow control means for disabling the evaporation process individually by blocking the refrigerant passage from said main expansion valve;c) each of said two evaporators including flow control means for providing a refrigerant passage from said main compressor to said two evaporators individually;d) each of said two evaporators including a heat insulated space, and said heat insulated space including individual outdoor-air-intake means;e) a control system for selecting defrosting methods and controlling all said flow control means and outdoor-air-intake means;f) said multi-range cross-reverse air-conditioning system is capable of defrosting each evaporator by a defrost-cycle of the cross-reverse defrosting process, wherein each of said evaporator will alternately operate with the cross-reverse defrosting process and the refrigerant evaporation process.

2. A cross-reverse type air-conditioning system as defined in claim 1, wherein; during the full capacity heating operation, all said evaporators will operate with the evaporation process; all refrigerant passages from said main compressor to each evaporator will be blocked to disable the refrigerant-flow associated with the cross-reverse defrosting process; a controlled flow of outdoor air is admitted into the heat insulated space of each evaporator by its associated outdoor-air-intake means.

3. A cross-reverse type air-conditioning system as defined in claim 1, wherein; during the cross-reverse defrosting process of each evaporator, said outdoor-air-intake means will stop inhaling outdoor air into the heat insulated space of the evaporator that is defrosting; a controlled amount of the pressurized refrigerant will be distributed into the evaporator that is defrosting, the accumulated frost on said evaporator will be melt by the heat generated from the condensation process; the other evaporator will continue the evaporation process with a flow of outdoor air, the main compressor and the main condenser will continue their operation to generate the heat energy for the air-conditioning.

4. A cross-reverse type air-conditioning system as defined in claim 1, which further comprises additional evaporators; wherein each of said additional evaporators includes individual flow control means for commencing the cross-reverse defrosting process; during the defrost-cycle of the cross-reverse defrosting process, the evaporator that is defrosting will receive a portion of the pressurized refrigerant from the main compressor, said evaporator will defrost with the heat energy generated by the condensation process therein.

5. A cross-reverse type air-conditioning system as defined in claim 1, wherein; the evaporator that is defrosting with the cross-reverse defrosting process will receive a flow of pressurized refrigerant from the main compressor, and said flow of pressurized refrigerant will condense in said evaporator and exit through its associated pressure regulating means into other evaporator that is operating with the evaporation process.

6. A cross-reverse type air-conditioning system as defined in claim 1, wherein; each evaporator can further comprise sensor means for detecting the progress of the cross-reverse defrosting process; and said control system can adjust the defrost-cycle accordingly for optimum heating efficiency.

7. A cross-reverse type air-conditioning system as defined in claim 1, wherein; said control system is capable to commencing a defrost-cycle of the cross-air defrosting process, wherein each of said evaporator will alternately operate with the cross-air defrosting process and the refrigerant evaporation process.

8. A cross-reverse type air-conditioning system comprising: a) a refrigeration circuit comprising of four sections, which are a refrigerant-compressing section, a refrigerant-condensing section, a refrigerant-evaporating section, and a cross-reverse section; said refrigerant-compressing section provides a flow of pressurized-refrigerant to said refrigerant-condensing section and said cross-reverse section; said refrigerant-condensing section will condense said flow of pressurized-refrigerant therein, and release the heat energy for air-conditioning; said refrigerant-condensing section will provide a flow of refrigerant to said refrigerant-evaporating section; said refrigerant-evaporating section absorbs heat from the outdoor environment and evaporates said flow of refrigerant therein, and then produces a flow of evaporated-refrigerant into said refrigerant-compressing section;b) said refrigerant-compressing section comprises at least one compressor (101);c) said refrigerant-condensing section comprises at least one main condenser (102);d) said refrigerant-evaporating section comprises at least two evaporator units, which are first-evaporator (121) and second-evaporator (122); each of said evaporator units has an individual heat insulated space and outdoor-air-intake;e) flow control means for independently controlling a refrigerant passage from said refrigerant-compressing section to said first-evaporator (121);f) flow control means for independently controlling a refrigerant passage from said refrigerant-compressing section to said second-evaporator (122);g) said cross-reverse section comprises a controlled refrigerant passage to each of said evaporator in said refrigerant-evaporating section; a first reverse-flow valve (151) for distributing a flow of pressurized refrigerant to said first evaporator (121) during the cross-reverse defrosting process of said first evaporator (121); a second reverse-flow valve (152) for distributing a flow of pressurized refrigerant to said second evaporator (122) during the cross-reverse defrosting process of said second evaporator (122);h) a control system for commencing the cross-reverse defrosting method and the cross-air defrosting method by controlling all said flow control means and outdoor-air-intake means;i) said multi-range cross-reverse air-conditioning system is capable of defrosting each evaporator by a defrost-cycle of the cross-reverse defrosting process, wherein each of said evaporator will alternately operate with the cross-reverse defrosting process and the refrigerant evaporation process.

9. A cross-reverse type air-conditioning system as defined in claim 8, wherein; during the full capacity heating operation, all said evaporators will operate with the evaporation process; said cross-reverse section will be disabled by shutting said first reverse-flow valve (151) and said second reverse-flow valve (152); a controlled flow of outdoor air is admitted into the heat insulated space of said first evaporator (121) and the heat insulated space of said second evaporator (122) by their associated outdoor-air-intake means.

10. A cross-reverse type air-conditioning system as defined in claim 8, wherein; during the cross-reverse defrosting process of said first evaporator (121), the refrigerant passage of said first evaporator (121) will be separated from said refrigerant-evaporating section by its associated flow control means, and first reverse-flow valve (151) will open to provide a flow of pressurized refrigerant into said first evaporator (121), therefore, the accumulated frost on said first evaporator (121) will melt by the heat energy generated by the condensation process therein, meanwhile said second evaporator (122) will operate with the evaporation process by absorbing the heat of the outdoor-air-flow, said main compressor (101) and said main condenser (102) will continue operation for the air-conditioning.

12. A cross-reverse type air-conditioning system as defined in claim 8, wherein; during the cross-reverse defrosting process of said second evaporator (122), the refrigerant passage of said second evaporator (121) will be separated from said refrigerant-evaporating section by its associated flow control means, and second reverse-flow valve (152) will open to provide a flow of pressurized refrigerant into said second evaporator (122), therefore, the accumulated frost on said second evaporator (122) will melt by the heat energy generated by the condensation process therein, meanwhile said first evaporator (121) will operate with the evaporation process by absorbing the heat of the outdoor-air-flow, said main compressor (101) and said main condenser (102) will continue operation for the air-conditioning.

13. A cross-reverse type air-conditioning system as defined in claim 8, which can further comprises additional evaporators; wherein each of said additional evaporators comprises individual flow control means and reverse-flow and outdoor-air-intake means for commencing the cross-reverse defrosting process.

14. A cross-reverse type air-conditioning system as defined in claim 8, wherein; said control system can employ a combination of the cross-reverse defrosting process and the cross-air defrosting process to maximize the heating efficiency of the air-conditioning.

15. A cross-reverse type air-conditioning system as defined in claim 8, wherein; each evaporator can further comprise sensor means for detecting the progress of the cross-reverse defrosting process; and said control system can adjust the defrost-cycle accordingly for optimum heating efficiency.

16. A cross-reverse type air-conditioning system as defined in claim 8, wherein; said control system will employ a defrost-cycle of the cross-reverse defrosting process when the outdoor temperature is within the range of 10 degree Celsius to negative 40 degree Celsius.

17. A forced-air-defrost type air-conditioning system as defined in claim 8, wherein; said control system will employ a defrost-cycle of the cross-air defrosting process when the outdoor temperature is within the range of 20 degree Celsius to 0 degree Celsius.