Patent Publication Number: US-2010131106-A1

Title: Method for efficient operation of cooling system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not Applicable 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable 
     THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT 
     Not Applicable 
     INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC 
     Not Applicable 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     Air-conditioner and cooling system. 
     2. Description of Related Art 
     This invention relates to efficient manipulation of cooling system(s) or air-conditioning to consume much less energy regarding when there is great change of temperature during the operation. Since upon each starting of the operation cycle of a compressor of an air-conditioner, energy is greatly consumed. Thus, too much energy is consumed unnecessarily especially at the time where there is big change and frequent change in room temperature. The thermostat is automatically off and on very frequently. The starting of the compressor is then very frequent as well, which in turn, energy is consumed much greater than really needed. To avoid such too great energy consumption during very frequent change of temperature, in prior arts, a system is developed to use the air-conditioner having the inverter compressor. Yet, the technology is too complicate, very difficult if repairing is needed, in addition to its expensive cost. The solution to such problem, the present invention describes a method for controlling of average cooling capacity of the system using, conventional compressor(s). The performance is more or less the same, but the technology is much simpler, easier for repairing and maintenance, and much cheaper. This newly invented system could be used with air-conditioning system of VRV (Variable Refrigerant Volume) type or multi-fancoil type. 
     SUMMARY OF THE INVENTION 
     A method for efficient operation of cooling system by using a system capable of controlling average cooling ability. The method describes controlling of injection of refrigerant ‘ON and ‘OFF’ into evaporator alternately according to preset period of time or preset differential room temperature by constructing circuits of specific arrangement of components of cooling system which are compressor, condenser, expansion valves, evaporator(s), evaporator pressure regulator, solenoid valves and/or a three-way valve. The method allows efficient controlling of operation of air-conditioning more or less similar to those system using Inverter to control the air-conditioning system. The present invention discloses a method to control cooling system with a much simpler technology, easy to repair or maintain and much less expensive, in addition to be able to apply with cooling system of the Variable Refrigerant Volume (VRV) type or multi-fancoil type. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a conventional cooling circuit of the prior arts. 
         FIG. 2  shows how solenoid valves V 1  and V 4  are added to a standard cooling circuit. 
         FIG. 3  shows adding of solenoid valve V 2  to the cooling circuit. 
         FIG. 4  shows how a three-way valve TWV 1  is used instead of solenoid valves to perform the same function. 
         FIG. 5  is a diagram showing controlling of the system at 50% average capacity through periods of operation time. 
         FIG. 6  is a diagram showing controlling of the system at 75% average capacity through periods of operation time. 
         FIG. 7  is a diagram showing controlling of average capacity of the system through deviation or differential room temperature of 0.5° C. 
         FIG. 8  shows use of Evaporator Pressure Regulator (EPR) instead of solenoid valve V 4  of circuit in  FIG. 3 . 
         FIG. 9  shows arrangement of circuit as a whole to be used in systems capable of averaging cooling capacity comprises sub-circuits having solenoid valve, expansion valve, evaporator and evaporator pressure regulator arranged in series to use in air-conditioning system of VRV or multi-fancoil type. 
         FIG. 10  shows how compressor, condenser and whole circuit of  FIG. 9  are connected in series arrangement. 
         FIG. 11  shows circuit of  FIG. 10  having solenoid valve V 0  whose inlet connecting from between condenser  2  and common tubing H 1 , and the other end connected to expansion valve R 0  whose outlet connected to in between common tubing H 2  and compressor  1  to help cooling the compressor. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  shows the circuit of a conventional air-conditioning system of the prior arts where the flow of refrigerant is compressed from compressor  1  into condenser  2  and passes through expansion valve  3  and injected into evaporator  4 , then back into compressor  1  to complete the circuit. For connecting a circuit of the present invention to improve the control of cooling system by means of controlling the average capacity of the system, is made as of  FIG. 2  and  FIG. 3  as follows: 
     As shown in  FIG. 2 , solenoid valve V 1  is added in between condenser  2  and expansion valve  3 , and solenoid valve V 4  is placed in between evaporator  4  and compressor  1 . Solenoid valves V 1  and V 4  are installed according to direction of the flow of refrigerant.  FIG. 3  shows that solenoid valve  2  is further inserted such that its inlet is connected from between solenoid valve V 1  and condenser  2  where its outlet is connected to expansion valve  5  whose outlet is connected to in between solenoid valve V 4  and compressor  1 . 
     The control is performed by controlling the turning on and off of the solenoid valves. Solenoid valves V 1  and V 4  is turning on and off simultaneously, but opposite to solenoid valve  2 . The operation is as follows: when solenoid valves V 1  and V 4  are ‘ON’, solenoid valve V 2  is ‘OFF’. Compressor  1  compresses refrigerant to flow through condenser  2 , to solenoid valve V 1  and further into expansion valve  3 , to have the refrigerant fully injected into the evaporator  4 , through solenoid valve V 4  and then back to compressor  1  to complete the circuit. This is the condition of “FULL LOAD’ where compressor uses the maximum electrical energy. But when solenoid valves V 1  and V 4  are ‘OFF’, solenoid valve V 2  will be ‘ON’, then there is no injection of refrigerant into evaporator  4 . This is a condition of ‘NO LOAD’ where minimum electrical energy is used. The operation is alternately performed by controlling through period of operation time or through differential room temperature by presetting of a timer and/or a thermostat, respectively. 
     Solenoid valve V 2  is ‘ON’ to allow the least volume of refrigerant to flow into expansion valve  5 , yet sufficiently only to allow cooling of compressor  1 . The fact is that under this ‘NO LOAD’ condition, the superheat of the system is very high that it can damage the compressor. Thus, the volume and the frequency of injection of the refrigerant need to be optimized to be the least, yet able to cool the compressor. On the other hand, too much of refrigerant can in turn harm the compressor. Control is possible thus by injection of refrigerant at all time in the system but variable where the volume of the refrigerant under ‘NO LOAD’ condition must be optimized to be the least as possible. 
     Control of the operation of cooling system by means of turning solenoid valve ‘ON’ and ‘OFF’ through a control system using timer or thermostat, as a result this can in turn control injection or stop injection of refrigerant into evaporator. This allows controlling the flow of refrigerant within the air-conditioning system. By varying the period or duration of turning ‘ON’ and ‘OFF’ of solenoid valves alternately for each predetermined period, this results in capability of controlling the operation of the air-conditioning system. 
     For example, as shown in  FIG. 5 , for each period of 20 seconds, solenoid valves V 1  and V 4  are turned ‘ON’ and inject refrigerant into evaporator for 10 seconds. This condition sets the system in ‘FULL LOAD’. When solenoid valves V 1  and V 4  are turned ‘OFF’, the system is then in ‘NO LOAD’ condition. Therefore, to average the flow rate of the refrigerant is as follows:
     A period of 20 seconds, injecting refrigerant for 20 seconds, equals 100% flow rate.   A period of 20 seconds, injecting refrigerant for 10 seconds, equals 50% flow rate.   

     Therefore, at 50% flow rate, the average capacity of the system is controlled at 50%. 
     Likewise, as shown in  FIG. 6 , injection of refrigerant for 15 seconds of total period of 20 sec allows flow rate of 75% and results in the average capacity of 75%. 
       FIG. 7  shows that when room temperature is set at 24° C., having a preset differential room temperature of 0.5° C. for controlling by thermostat the turning ‘ON’ and ‘OFF’ of the solenoid valves. The process is that at the beginning, solenoid valve V 2  is ‘OFF’, while solenoid valves V 1  and V 4  are ‘ON’, the compressor thus operates in ‘FULL LOAD’ condition. When the room temperature is down to 24° C., the controlling system turns solenoid valves V 1  and V 4  ‘OFF’. And V 2  ‘ON’ to have the compressor in “NO LOAD’ condition. Only until the room temperature rises to 24.5° C., solenoid valve V 2  is then turned ‘OFF’ and solenoid valves V 1  and V 4  are ‘ON’ to let the compressor back to ‘FULL LOAD’ condition. Therefore, the system is ‘ON’ and ‘OFF’ alternately to keep the fluctuation of room temperature within only 0.5° C. 
     Therefore, by controlling the flow rate of the refrigerant in the cooling system, it is possible to efficiently control the cooling system through the so-called its ‘average capacity’. 
     The operation of the system is such that, at all time of operation, there is no time point that compressor stop operating thus there is no starting of compressor at any time during operation time. This is distinctly different than that of the system utilizing inverter and thus helps energy-saving since electrical surge does not occur due to no need to start the compressor. During the operation, the capacity of the cooling system is very well controlled to meet the requirement by controlling the average flow rate operating between condition of ‘FULL LOAD’ and ‘NO LOAD’ in each period of operation. The result is that utilization of energy is controlled and optimized to meet the requirement, where during ‘FULL LOAD’ condition energy consumption is the highest and during ‘NO LOAD’ condition energy consumption is the minimum. The average value for operation can be determined similar to that of determining average capacity of the cooling system. This helps that average electrical power consumed equals to what really needed for the operation. There is no excess use of energy unnecessarily. Thus, the present invention operates similarly to the system using inverter, yet with less energy consumption, much less complicate, and easier for repairing or maintenance. 
     As shown in  FIG. 4 , removing solenoid valves V 1  and V 2  of circuit of  FIG. 3  and a three-way valve TWV 1  is put in place having its inlet connected from condenser  2  and its first outlet connected to expansion valve  3  while its second outlet connected to expansion valve  5 . 
     Controlling of cooling system of  FIG. 4  is performed as follows: solenoid V 4  and first outlet of three-way valve TWV 1  are ‘ON’ and ‘OFF’ at the same time but opposite to the second outlet of three-way valve TWV 1 . Thus, at step  1 , solenoid V 4  and first outlet of three-way valve TWV 1  are ‘ON’. Refrigerant is compressed from compressor  1  through condenser  2  out through first outlet of three-way valve TWV 1  into expansion valve  3  and fully forced into evaporator  4 , then back to compressor  1  to complete the circuit. This is the condition the system operates in ‘FULL LOAD’ and energy is consumed at highest level. 
     In a different condition, when solenoid valve V 4  is ‘OFF’ where the first outlet of three-way valve TWV 1  is also ‘OFF’, the second outlet of the three-way valve TWV 1  is ‘ON’ and having the refrigerant in least amount to flow through to expansion valve  5  and back to compressor  1 . There is then NO refrigerant in evaporator  4 . The cooling system thus operates under ‘NO LOAD’ condition, where compressor uses the least electrical. energy. The system is alternately operating depends on the rhythm of preset period or the preset differential room temperature like that of  FIG. 3 . 
       FIG. 8  shows that Evaporator Pressure Regulator (EPR) is used instead of solenoid valve V 4  of circuit shown in  FIG. 3 , to regulate the evaporating temperature of the refrigerant (for air-conditioner the temperature for evaporating the refrigerant is about 5° C.). To regulate the pressure of refrigerant in evaporator  4 , solenoid valves V 1  and V 2  are turning ‘ON’ and ‘OFF’ oppositely. In the first step, solenoid valve V 1  is ‘ON’ while solenoid valve V 2  is ‘OFF’. This allows the cooling system to operate under ‘FULL LOAD’ condition. When solenoid valve V 1  is ‘OFF’, solenoid valve V 2  is then ‘ON’ and let the system operate under ‘NO LOAD’ condition. As solenoid. valve V 2  is ‘ON’, refrigerant in least volume flows into expansion valve  5  to cool compressor  1 . The system operates alternately depends on the preset period of operation or the preset differential room temperature in the same manner as that of  FIG. 3 . 
       FIGS. 9 ,  10  and  11  show the process utilizing this invented cooling system with averaging capacity described in the present invention to apply with VRV type or multi-fancoil type, where one condensing unit can be connected to 2 units of fancoil and up. Each unit operates independently depending on the load of each unit as follows: 
     In  FIG. 9 , many fancoils are connected in parallel, each sub-circuit is connected in parallel where each sub-circuit consists of components arranged in series according to flow direction of the refrigerant. In sub-circuit No. 1, refrigerant flows through solenoid valve V 1  into expansion valve R 1  which injects refrigerant fully into evaporator E 1  and out through evaporator pressure regulator EPR 1 . For sub-circuit No. 2, refrigerant flows through solenoid valve V 2  into expansion valve R 2  which injects refrigerant fully into evaporator E 2  and out through evaporator pressure regulator EPR 2 . For sub-circuit No. n, refrigerant flows through solenoid valve Vn into expansion valve Rn which injects refrigerant fully into evaporator En and out through evaporator pressure regulator, EPRn. The sub-circuits are arranged in parallel where refrigerant flows in to the side of solenoid valve Vn from a common tubing called Header  1 , H 1 . Refrigerant flows out from evaporator pressure regulator, EPRn to pool into a common tubing called Header  2 , H 2 . 
     As shown in  FIG. 10 , inlet of compressor  1  is connected to common tubing H 2 , and condenser  2  is connected between tubing from compressor  1  and common tubing H 1 , thus makes the main circuit complete. According to  FIG. 11 , inlet of solenoid valve V 0  is connected from between common tubing H 1  and condenser  2 , where its outlet connected to expansion valve R 0  and outlet of expansion valve R 0  is connected in between common tubing H 2  and compressor  1 . Therefore, the air-conditioning system of multi-fancoil is thus equipped with the controlling system capable of averaging the cooling ability to keep the temperature under control. 
     The operation starts with compressor  1  compresses the refrigerant from all evaporators fully into condenser  2 , the refrigerant flows into common tubing H 1 , and distributed into each sub-circuit at all time that solenoid valve Vn is ‘ON’. Each sub-circuit operates independently within its sub-circuit. The size of each fancoil depends on the ‘LOAD’ it assigned which needs not be equal for all the sub-circuits. The size of each expansion valve Rn is equal and sufficient to inject refrigerant fully into evaporator En which is the volume for ‘FULL LOAD’ operation of its sub-circuit. The evaporator pressure regulator, EPRn, functions by regulating the pressure within the evaporator En to be constant to have the evaporating temperature is as preset. For instance, air-conditioner set the evaporating temperature at about 5° C. The operation of the main circuit is the summing up of the operation of all the sub-circuit. The capacity of compressor  1  thus equals to the capacity at ‘FULL LOAD’ condition of all the fan coils summed up. Condenser  2  must have the size big enough to cool down the heat results from operation at ‘FULL LOAD’ condition of compressor  1  summed up with the heat of compressor  1  itself. 
     The operation of each sub-circuit is possible independently by controlling the turning ‘ON’ and ‘OFF’ of solenoid valve Vn in each sub-circuit according to the preset period of operation or the preset differential room temperature (ΔT). Yet independency of each sub-circuit results in superheating and can damage compressor  1 . When superheating occurs, the solenoid valve V 0  thus must turn ‘ON’ to inject optimum volume of refrigerant through expansion valve R 0  to cool compressor  1  efficiently and prevent compressor  1  from being damaged (yet the optimal volume must be used as too much will also harm the compressor). Alternatively, solenoid valve V 0  is controlled to be ‘ON’ at all time where very small amount of refrigerant is used and easy to regulate. 
     As a result, average capacity of each sub-circuit can be controlled by using only one condensing unit and compressor at least one unit. As a result, air-conditioning system of VRV type or multi-fancoil type can use this system of average cooling capacity to control the system much simpler, easier for repairing and maintenance, and much cheaper than the inverter compressor. 
     It will be understood that modifications can be made in the above description without departing from the scope of this invention by one of ordinary skill in the art. It is accordingly intended that all matter contained in the above description be interpreted as descriptive and illustrative rather than in a limiting sense. It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention as described herein, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.