Description

AIR CONDITIONING SYSTEM FOR COMMUNICATION EQUIPMENT AND CONTROLLING METHOD THEREOF

Technical Field

[1] The present invention relates to an air conditioning system for communication equipment and a method for controlling the same, and more particularly, to an air conditioning system for alternatively operating a plurality of cooling units in itself such that a operating load for cooling the communication equipment is not concentrated on only one or some cooling units.

[2]

Background Art

[3] As is generally known in the art, an airconditioner employs evaporation heat which a refrigerant absorbs from surroundings when it evaporates. Typically, as refrigerant, liquids such as, ammonia, Freon, azeotropic refrigerant mixture, and chloromethyl which is easily evaporated at relatively low-temperatures.

[4] Typically, the air conditioner performs following processes: High-pressure vaporized refrigerant compressed by a compressor is changed into high-pressure refrigerant liquefied by heat exchange with outdoor air at a condenser; The high-pressure liquefied refrigerant is changed into low-pressure vaporized refrigerant by an expansion value and a capillary; and The low-pressure vaporized refrigerant flowed into an evaporator is evaporated by heat exchange with indoor air and the evaporated refrigerant is flowed back into the compressor. The refrigerant flowed into the compressor repeatedly circulates by the above processes. Air cooled by evaporation heat of the refrigerant occurred at the evaporator is blown into a predetermined space or objects to be cooled.

[5] As described above, a conventional air conditioner can cool objects by using characteristics of refrigerant to which a phase change, e.g.,condensation and evaporation easily occurs.

[6] In the meanwhile, there are many kinds of wire or wireless communication equipment in the base communication station or communication vehicles. Typically, heat resulted from the operation of the communication equipment may cause malfunction by breakdown of components in communication equipment or a contact error between two nodes in communication equipment. For this reason, it is necessary to cool the communication equipment all year round to minimize malfuction if the communication equipment due to heat generation therein.

[7] There is a problem that the conventional air conditioner for communication equipment does not appropriately use outdoor air or indoor air to cool the com-

munication equipment according to surrounding temperature of the communication equipment. Also, there is another problem that since the conventional air conditioner is continueously operated by external power source, the power consumption of the conventional air conditioner is very high and the cooling efficiency of itself is very low.

[8] In order to solve the problem described above, Applicant invented an air conditioning system for communication equipment and a method for controlling the air conditioning system being able to reduce power consumption by operating selectively a outdoor unit and filed an application (Korea application number 10-2005-0014790) regarding the same.

[9] However, the application has a problem that in case that more cooling units with a first cooling unit are required in the air conditioning system while indoor temperature becomes relatively high, only a selected cooling unit is continuously operated. Therefore, the durability of the air conditioning system decreases and the breakdown rate of the air conditioning system increases. Then, the repair cost of the air conditioning system increases. That is, the air conditioning system is not economical.

[10]

Disclosure of Invention Technical Problem

[11] The present invention is directed to provide an air conditioning system for communication equipment and a method for control the air conditioning system to alternatively operate a plurality of cooling units in itself such that a operating load for cooling the communication equipment is not concentrated on only one or some cooling units.

[12] Also, the present invention is directed to provide an air conditioning system for communication equipment and a method for control the air conditioning system to enhance the durability of the air conditioning system, to decrease the breakdown rate of the air conditioning system and to reduce the repair cost of the air conditioning system by alternatively operating a plurality of cooling units in the air conditioning system.

[13]

Technical Solution

[14] In accordance with an aspect of the present invention, there is provided an air conditioning system for communication equipment including a first cooling unit, a second cooling unit, and a third cooling unit.

[15] The first cooling unit includes an outdoor heat exchanger for exchanging heat with outdoor air, an indoor heat exchanger for exchanging heat with indoor air, a circulating pipe for circulating a first refrigerant, a circulate pump arranged on a predetermined position of the circulating pipe, a refrigerant temperature sensor arranged on an

outdoor predetermined position of the circulating pipe, a bypass pipe for circulating the first refrigerant to avoid passing through the outdoor heat exchanger, a first and a second bypass valves arranged on the circulating pipe and the bypass pipe, respectively, a first heat exchange tube arranged on the circulating pipe, a first brine heat exchanger having the first heat exchange tube therein, an indoor temperature sensor for measuring indoor temperature of a base station, and an outdoor temperature sensor for measuring outdoor temperature of the base station.

[16] The second cooling unit includes a first compressor for changing a second refrigerant into a high-temperature and high-pressure second refrigerant, a first condenser for exchanging heat between outdoor air and the high-temperature and high-pressure second refrigerant, a first expansion valve for changing the second refrigerant provided from the first condenser into a low-temperature and low-pressure second refrigerant, a first evaporator for exchanging heat with the first heat exchange tube wherein the first evaporator is arranged in the first brine heat exchanger arranged between the first expansion valve and the first compressor.

[17] The third cooling unit includes a second compressor for changing a third refrigerant into a high-temperature and high-pressure third refrigerant, a second condenser for exchanging heat between outdoor air and the high-temperature and high-pressure third refrigerant, a second expansion valve for changing the third refrigerant provided from the condenser into low-temperature and a low-pressure third refrigerant; and a second evaporator arranged between the second expansion valve and the second compressor wherein the first cooling unit includes a second heat exchange tube arranged at an outlet of the first second heat exchange tube and a second brine heat exchanger having the second heat exchange tube and the second evaporator therein.

[18] In accordance with another aspect of the present invention, there is provided a method for controlling the air conditioning system includes a first step of measuring indoor temperature; a second step of operating a first cooling unit if the indoor temperature is between a first reference temperature and a second reference temperature; a third step of checking whether a second cooling unit is operated or not if the indoor temperature is between a second reference temperature and a third reference temperature; and a fourth step of operating the second cooling unit or a third cooling unit according to the checked result.

[19]

Advantageous Effects

[20] The air conditioning system for communication equipment and a controlling method thereof according to present invention can control a operating load for cooling the communication equipment not to be concentrated on only one or some cooling units by

alternatively operating a plurality of cooling units in itself. Thus, the air conditioning system for communication equipment and a controlling method thereof according to present invention can enhance the durability of the air conditioning system, decrease the breakdown rate of the air conditioning system, and thereby reduce the repair cost of the air conditioning system. This is to say, the air conditioning system for communication equipment and the controlling method thereof according to present invention is very economical. Also, even though one or more of a plurality of cooling units arranged in the air conditioning system is out of order, the air conditioning system according to the present invention can stably cool the communication equipment.

[21]

Brief Description of the Drawings

[22] Fig. 1 is a block diagram showing an air conditioning system for communication equipment in accordance with an embodiment of the present invention.

[23] Fig. 2 is a block diagram showing a cooling operation using a first cooling unit in an air conditioning system for communication equipment in accordance with an embodiment of the present invention.

[24] Fig. 3 is a block diagram showing a cooling operation using a first cooling unit and a second cooling unit in an air conditioning system for communication equipment in accordance with an embodiment of the present invention.

[25] Fig. 4 is a block diagram showing a cooling operation using a first cooling unit to a third cooling unit in an air conditioning system for communication equipment in accordance with an embodiment of the present invention.

[26] Figs. 5 and 6 are a flow chart illustrating a method for controlling an air conditioning system for communication equipment in accordance with an embodiment of the present invention.

[27]

Best Mode for Carrying Out the Invention

[28] Hereinafter, an exemplary embodiment of the present invention will be described in detail with reference to drawings provided according to the embodiment of the present invention.

[29] Fig. 1 is a block diagram showing an air conditioning system for communication equipment in accordance with an embodiment of the present invention.

[30] As shown, the air conditioning system for communication equipment in accordance with an embodiment of the present invention includes a first cooling unit 100 for directly cooling the communication equipment (not shown), and a second and a third cooling units 200 and 300 for indirectly cooling the communication equipment by

cooling a first refrigerant of the first cooling unit 100. The first, second, and third cooling units 100, 200, and 300 are arranged in an indoor unit 500 and an outdoor unit 600. The indoor unit 500 is arranged with the communication equipment in a base station. The outdoor unit 600 is arranged outside the base station. The indoor unit 500 includes a temperature sensor 510 for measuring indoor temperature and the outdoor unit 600 includes a temperature sensor 610 for measuring outdoor temperature.

[31] The first cooling unit 100 is first described hereinafter. An indoor heat exchanger 110 arranged in the indoor unit 500 is a component for heat exchange between indoor air and the first refrigerant. A first temperature sensor 112 is arranged at an inlet of the indoor heat exchanger 110 and a second temperature sensor 114 is arranged at an outlet of the indoor heat exchanger 110. Indoor fans 116 are arranged at one side of the indoor heat exchanger 110 for transferring air cooled by heat exchange of the indoor heat exchanger 110. Outdoor heat exchangers 120 are arranged at the outdoor unit for heat exchange between outdoor air and the first refrigerant. The outdoor heat exchangers 120 are arranged in series or in parallel with reference to a position of outdoor fans 122. The indoor heat exchanger 110 and the outdoor heat exchangers 120 are connected by a circulating pipe 130 filled with the first refrigerant.

[32] As described above, the circulating pipe 130 is filled with the first refrigerant and the first refrigerant circulates through the circulating pipe 130. A circulation pump 132 compulsively circulates the first refrigerant through the circulating pipe 130. A pressure switch 134 measures pressure of the first refrigerant at the inlet of the indoor heat exchanger 110. A flow switch 136 measures the flow amount of the first refrigerant at the outlet of the indoor heat exchanger 110.

[33] A heat coil 180 and a refrigerant temperature sensor 190 are arranged on the portion of the circulating pipe 130 installed in the out door unit 600, and the heat coil 180 prevents the circulation pipe 130 from being broken by cold weather. Also, a first heat exchange tube 162 and a second heat exchanged tube 164 are arranged in series on the circulating pipe 130 wherein the first heat exchange tube 162 is for exchanging heat with a first evaporator 240 of the second cooling unit 200 and the second heat exchange tube 164 is for exchanging heat with a second evaporator 340 of the third cooling unit 300. The first brine heat exchanger 172 has the first heat exchange tube 162 therein and the second brine heat exchanger 174 has the second heat exchange tube 164 therein.

[34] A bypass pipe 140 is arranged for circulating the first refrigerant so that the first refrigerant avoid passing through the outdoor heat exchangers 120. A first bypass valve 152 is provided on the circulation pipe 130 and a second bypass valve 154 is provided on the bypass pipe 140. The first bypass valve 152 and the second bypass valve 154 can be opened at the same time or a selected one of the two valves 152 and 154 can be

opened.

[35] The circulation pump 132 includes a pair of pumping units which are connected in parallel. If one of the pumping units is out of order, since the other can be normally operated, circulation of the refrigerant can be carried out. Thus, cooling operation of the first cooling unit 100 can be regularly performed. Herein, as described above, the heat coil 180 is for preventing components of the air conditioning system from being damaged with cold.

[36] The second cooling unit 200 includes a first compressor 210 for changing a second refrigerant into a high-temperature and high-pressure second refrigerant, a first condenser 220 for exchanging heat between outdoor air and the high-temperature and high-pressure second refrigerant, a first expansion valve 230 for changing the second refrigerant provided from the first condenser 220 into a low-temperature and low- pressure second refrigerant, the first evaporator 240 arranged in the first brine heat exchanger 172 exchanges heat with the first heat exchange tube 162. Herein, the first evaporator 240 is arranged between the first expansion valve 230 and the first compressor 210.

[37] The third cooling unit 300 includes a second compressor 310 for changing a third refrigerant into a high-temperature and high-pressure third refrigerant, a second condenser 320 for exchanging heat between outdoor air and the high-temperature and high-pressure third refrigerant, a second expansion valve 330 for changing the third refrigerant provided from the condenser into a low-temperature and low-pressure third refrigerant, and the second evaporator 340 arranged between the second expansion valve 330 and the second compressor 310. Herein, the second evaporator 340 is for exchanging heat with a second heat exchange tube 164 and is arranged in a second brine heat exchanger 174.

[38] The first refrigerant used in the first cooling unit 100 according to the present invention includes water. The second refrigerant used in the second cooling unit 200 and the third refrigerant used in the third cooling unit 300 includes one selected from the group consisting of ammonia, azeotropic refrigerant and chloride methyl, or combinations thereof.

[39] A cooling operation of the air conditioning system according to the present invention is described hereinafter. The cooling operation is controlled according to indoor temperature and the outdoor heat exchangers 120 is controlled according to outdoor temperature and the temperature of the first refrigerant. Herein, the first refrigerant includes brine.

[40] First, the indoor temperature of the base station is measured. If the measured indoor temperature is higher than a first reference temperature, e.g., 25 degrees, the first cooling unit is operated (Referring to Fig. 2). This case is called a first cooling

operation. In this case, if outdoor temperature is lower than that of the first refrigerant, the first bypass valve 152 is opened and the outdoor heat exchangers 120 is operated. Herein, the second bypass valve 154 is closed. If outdoor temperature is higher than that of the first refrigerant, the second bypass valve 154 is opened and the operation of the outdoor heat exchangers 120 is stopped. Herein the first bypass valve 152 is closed.

[41] If the measured indoor temperature is higher than a second reference temperature, e.g., 26.5 degrees, the first cooling operation is not sufficient to cool the indoor space of the base station. In this case, both of the first cooling unit 100 and the second cooling unit 200 are operated. This case is called a second cooling operation (Referring to Fig. 3). While the first cooling unit 100 and the second cooling unit 200 are operated, heat exchange between the first refrigerant and the second refrigerant is performed in the first brine heat exchanger 172. The first refrigerant cooled by the above heat exchange is used to cool communication equipment in the base station.

[42] Also, if the measured indoor temperature is higher than a third reference temperature, e.g., 27.5 degrees, the second cooling operation is not sufficient to cool the indoor space of the base station. In this case, all of the firts, second, and third cooling units 100, 200, and 300 are operated. This case is called a third cooling operation. During the third cooling operation, heat exchange between the first refrigerant and the second refrigerant is first performed in the first brine heat exchanger 172 and heat exchange between the first refrigerant and the third refrigerant is secondly performed in the second brine heat exchanger 174. The first refrigerant cooled by the above heat exchanges is used to cool communication equipment in the base station.

[43] As described above, if outdoor temperature is lower than that of the first refrigerant during the second cooling operation and the third cooling operation, the first bypass valve 152 is opened and the outdoor heat exchangers 120 is operated. If outdoor temperature is higher than that of the first refrigerant during the second cooling operation and the third cooling operation, the second bypass valve 154 is opened and the operation of the outdoor heat exchangers 120 is stopped.

[44] Referring to Figs 1 to 6, hereinafter, it is described a method for control air conditioning system for communication equipment and a controlling method thereof according to present invention.

[45] Fig. 5 is a flow chart illustrating a method for controlling an air conditioning system in accordance with an embodiment of the present invention in case that the indoor temperature T m is between a first reference temperature T si , e.g., 25 degrees and a third reference temperature T , e.g., 27.5 degrees. First, a temperature in the base station, that is, the indoor temperature T is measured (S 102). The first cooling unit 100 is operated (S 106) if the indoor temperature T is between the first reference temperature

T and a second reference temperature T , i.e., 26.5 degrees (S 104).

[46] While the first cooling unit 100 is operated, it is checked whether the third cooling unit 300 is operated or not (S 110) if the indoor temperature T is between the second reference temperature T and the third reference temperature T (S 108). If the third cooling unit 300 is operated, the second cooling unit 200 is further operated (Sl 12). If the third cooling unit 300 is not operated, the third cooling unit 300 is further operated (Sl 14). This is to say, the second cooling unit 200 and the third cooling unit 300 are alternatively operated.

[47] As described above, if a predetermined time is passed after the first cooling unit 100 and the second cooling unit 200 are operated, the second cooling unit 200 is stopped and the operation of the third cooling unit 300 is started (Sl 16). Also, if the predetermined time is passed after the first cooling unit 100 and the third cooling unit 300 are operated, the third cooling unit 300 is stopped and the operation of the second cooling unit 200 is started (Sl 18). Herein, the predetermined time is preferably 6 hours.

[48] In the meantime, on condition that all of the firts, second, and third cooling unit 100,

200, and 300 are not operated, if the outdoor temperature is below the first refrigerant temperature although the measured indoor temperature T is above the second reference temperature T , the second cooling unit 200 and the third cooling unit 300 are not started to operate but only the first cooling unit 100 is started to operate for a predetermined time, e.g., 5 minutes. Then, the indoor temperature Tin is measured again and it is decided whether one or both of the second cooling unit 200 and the third cooling unit 300 are started to operate. If the second cooling unit 200 and the third cooling unit 300 are operated in case that the operation of the first cooling unit 100 can sufficiently cool communication equipment, needless power consumption of the air conditioning system can occur and also, durability of the second cooling unit 200 and the third cooling unit 300 may decrease.

[49] Fig. 6 is a flow chart illustrating a method for controlling an air conditioning system in accordance with an embodiment of the present invention in case that the indoor temperature T is above a third reference temperature T . As shown in Fig. 6, if the m s3 indoor temperature T is above the third reference temperature T on condition that the m s3 first and second cooling unit 100 and 200 are operated or the first and third cooling unit 100 and 300 are operated (S 122), it is checked whether the third cooling unit 300 is operated or not (S 124). If the third cooling unit 300 is operated, the second cooling unit 200 is further operated (S 126). If the third cooling unit 300 is not operated, the third cooling unit 300 is further operated (S 128).

[50] Thereafter, it is checked whether the second cooling unit 200 is operated or not if the indoor temperature T is between the second reference temperature T and the third reference temperature T . If the second cooling unit 200 is operated, the second

cooling unit 200 is stopped to operate (S 134). If the second cooling unit 200 is not operated, the third cooling unit 300 is stopped to operate (S136).

[51] As described above, if the second cooling unit 200 and the third cooling unit 300 are alternatively operated, a operating load for cooling the communication equipment is not concentrated on the second cooling unit 200 or the third cooling unit 300. Thus, the air conditioning system for communication equipment can enhance the durability and decrease the breakdown rate of itself. Also, since the air conditioning system can reduce the repair cost of the air conditioning system becuase of that, the air conditioning system is economical.

[52] If the second cooling unit 200 or the third cooling unit 300 has a problem on condition that the first and second cooling units 100 and 200 or the first and third cooling units 100 and 300 are operated, display alarm is announced and the one cooling unit having a problem is stopped to operate. Then, the other cooling unit not having a problem is started to operate. In that case, if the other cooling unit has a problem, i.e., both of the second and third units have a problem, display alarm is announced and the other cooling unit is stopped to operate.

[53] If it is possible to cool the communication equipment with outdoor natural air, i.e., outdoor temperature is lower than the first refrigerant temperature, the first bypass valve 152 is opened and the outdoor unit 600 is normally operated. Alternatively, if it is not possible to cool the communication equipment with outdoor natural air, i.e., outdoor temperature is higher than the first refrigerant temperature, the second bypass valve 154 is opened and the operation of the outdoor unit 600 is stopped. It prevents indoor temperature from increasing by heat exchange between the first refrigerant and relatively warm outdoor air. If the outdoor temperature becomes lower afterward, it is started to cool the communication equipment with outdoor natural air.

[54] While the present invention has been described with respect to certain preferred embodiments, it will be apparent to those skilled in the air that various changes and modifications may be made without departing from scope of the invention as defined in the following claims.