JP2012193903A - Air conditioning system using outside air, and outside air heat exchange system of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maximize the coefficient of performance of an outside air heat exchange system or air conditioning system using outside air.SOLUTION: In a control device 30, the coefficient of performance and an estimated coefficient of performance are determined based on a measured temperature in the charge and discharge of the outside air by thermometers 21, 22, the power consumption of a fan 11b and a pump 13 by power meters 23, 24, and the number of rotations and virtual number of rotations of the fan 11b, and based on the magnitude correlation of the determined coefficients, the number of rotations of the fan 11b is increased or decreased so as to improve the coefficient of performance.

Description

  The present invention relates to an air conditioning system that uses outside air.

Conventionally, there is an air conditioning system that uses outside air (hereinafter, an outside air-using air conditioning system).
Such an outside air-use air conditioning system is installed in a server room / data center, for example. Here, as an example, the air-conditioning target space will be described as a server room in which a large number of server devices are installed, but the present invention is not limited to this example.

  In the case of the server room, the server device (computer; its CPU, etc.) in operation is a main heat source, and cooling is required even when the outside air temperature is low as in winter. On the other hand, by using this, mainly in the period when the outside air temperature is relatively low except during summer, energy saving of the air conditioner is achieved by using the outside air by an auxiliary action.

  That is, first, an air conditioning system using a general refrigeration cycle such as a vapor compression type is installed in the server room. As is well known, in such an air conditioning system using a refrigeration cycle, refrigerant is circulated to each device (compressor, condenser, expansion valve, evaporator) using piping, and the refrigerant is compressed. It is compressed by a machine, cooled by a condenser to produce a high-pressure liquid, the pressure is reduced by an expansion valve, vaporized at a low temperature by an evaporator, and the surrounding heat is taken away by the heat of vaporization. Return air (warm air) from the server room is cooled by passing it through an evaporator to generate cool air. The generated cold air is supplied to the server room to cool the server device that generates heat, and becomes warm air, and the warm air is again passed through the evaporator as described above.

In general, a unit (air handling unit) having the above-described evaporator and a fan for intake of return air or exhaust of cold air is provided indoors.
Note that the above-described general air compression system such as a vapor compression type refrigeration cycle may be simplified and referred to as an “air conditioning system using a refrigeration cycle”, a “general air conditioning system”, or the like.

  Here, in the said outside air utilization air conditioning system, in addition to the said general air conditioning system, the outside air heat exchange system is further provided. This outdoor air heat exchange system cools return air (warm air) from the server room and lowers its temperature in the front stage of the air handling unit described above. Thereby, since the temperature of the warm air flowing into the air handling unit is lowered, the cooling load in a general air conditioning system can be reduced, and the power consumption can be reduced. In addition, although some electric power consumption arises in an external air heat exchange system, this is a very small thing compared with the reduction amount of the electric power consumption of a general air conditioning system. Therefore, the power consumption as a whole is smaller than that of a general air conditioning system alone, and an energy saving effect is obtained.

  The configuration of the outdoor air heat exchange system is, for example, a system in which heat exchangers are provided outdoors and indoors, a pipe is connected between the two heat exchangers, and a coolant (for example, water) is circulated in the pipe. It is. For example, the coolant is circulated by power such as a pump. Here, a heat exchanger installed outdoors is referred to as an “air-cooled heat exchanger”, and a heat exchanger installed indoors is referred to as a “heat exchanger” as it is.

  The outside air is passed through the “air-cooled heat exchanger”. In this method, outside air is sucked and exhausted using a fan or the like. As described above, the coolant (for example, water) also passes through the “air-cooled heat exchanger”, and heat exchange is performed between the outside air and the coolant.

  Similarly, the return air (warm air) is passed through the “heat exchanger”. This uses a fan or the like to intake and exhaust return air. As described above, the coolant (for example, water) also passes through the “heat exchanger”, and heat exchange is performed between the return air and the coolant.

  Here, in any of the “air-cooled heat exchanger” and the “heat exchanger”, as a matter of course, in the heat exchange, heat is transferred from a higher temperature to a lower temperature. Therefore, for example, in winter, the outside air temperature is lower than the temperature of the coolant flowing into the “air-cooled heat exchanger”, so the coolant is cooled by the outside air. In the “heat exchanger”, the return air (warm air) is cooled by the coolant thus cooled by the outside air.

  However, in the “air-cooled heat exchanger”, when the outside air temperature is higher than the temperature of the coolant, the coolant is not cooled, and the temperature may rise. Although this is an extreme example, the heat exchange capacity obtained in the “air-cooled heat exchanger” varies depending on the outside air temperature. Basically, the higher the outside air temperature (in other words, the outside air and the coolant). The smaller the temperature difference is, the smaller the heat exchange capacity becomes.

  Here, when the cooling liquid medium is cooled by the air-cooled heat exchanger using the outside air as in the above-described outside air heat exchange system, the cooling medium is flowed into the air-cooling heat exchanger with a pump or the like as described above, and the outside air is Although it takes in with a fan, the heat exchange capability obtained changes with outside temperature. Furthermore, the heat exchange capacity obtained varies depending on the airflow of the fan. Increasing the fan air flow increases the cooling capacity, but at the same time increases the fan power (thus increasing power consumption), and the coefficient of performance (COP) (= per unit power consumption) is an index of cooling efficiency. In some cases, the cooling capacity (heat exchange amount) of the battery was reduced.

Here, conventionally, several examples are known in which the rotational speed of an outdoor fan is controlled to minimize power consumption. For example, conventional techniques described in Patent Documents 1 and 2 are known.
The invention of Patent Document 1 is an air conditioner including a compressor, an outdoor heat exchanger, an outdoor fan, an outdoor electric expansion valve, an indoor heat exchanger, an indoor electric expansion valve, and the like, and is close to a target air conditioning load point. The target air-conditioning operation is possible, and for example, by controlling the frequency of the compressor, the rotational speed of the outdoor fan, etc., the operation with the power consumption amount substantially minimized is enabled.

  Further, the invention of Patent Document 2 corrects the rotation speed of the compressor and the outdoor fan according to the difference between the room temperature and the room set temperature and the difference between the room humidity and the room set humidity during the dehumidifying operation. The dehumidifying operation is controlled so as to maximize the dehumidifying efficiency.

JP 2003-185219 A JP-A-11-304285

  The inventions of Patent Documents 1 and 2 described above all relate to control of an air conditioning system using a general refrigeration cycle such as a vapor compression type, and are applied to an outside air-use air conditioning system (outside air heat exchange system) as it is. However, an effective energy saving effect / performance coefficient improvement effect cannot be expected.

  That is, in the case of the inventions of Patent Documents 1 and 2, in order to preset the target cooling load, the minimum power consumption may be obtained and controlled from the relationship between the fan speed and the cooling load. However, in the case of the above-described outside air-utilizing air conditioning system, the air handling unit mainly handles the cooling load, and the outside air heat exchange system (such as an air cooling heat exchanger) is used as an auxiliary. Therefore, considering the cooling load of the air-cooled heat exchanger, it is necessary to perform the minimum power consumption operation for the entire system.

Further, as described above, in the case of an outside air-conditioning air conditioning system, when the outside air temperature is high or the like, it is counterproductive if the outside air heat exchange system is operated (the coefficient of performance decreases).
An object of the present invention is to calculate a coefficient of performance based on the amount of heat exchange with the outside air and power consumption in the outside air heat exchange system, and to control the fan rotation speed of the outside air heat exchange system based on the coefficient of performance. Furthermore, when the coefficient of performance falls below a predetermined threshold, the outside air heat exchange system is stopped, so that it can be operated with almost maximum efficiency in any outside air state, and the outside air conditioning system that can save energy, and the outside air heat exchange system. Etc. is to provide.

  The outdoor air-conditioning air-conditioning system of the present invention cools an air-conditioning system using a refrigeration cycle having an indoor unit that generates cold air, an indoor heat exchanger provided upstream of the indoor unit, and an air-cooled heat exchanger provided outdoors. An outdoor air heat exchange system that circulates liquid and causes heat exchange between the cooling liquid and indoor warm air in the indoor heat exchanger and heat exchange between the cooling liquid and outside air in the air-cooled heat exchanger; An air-conditioning system using outside air having power consumption measuring means for measuring power consumption of a pump for circulating the coolant and power consumption of a fan of the air-cooling heat exchanger, and passing through the air-cooling heat exchanger The temperature measuring means for measuring the supply air temperature and the exhaust temperature of the outside air and the power consumption measured by the power consumption measuring means are inputted and measured by the temperature measuring means. A control device that inputs the supply air temperature and the exhaust temperature and controls the rotational speed of the fan, and the control device determines the temperature difference between the supply air temperature and the exhaust temperature and the rotational speed of the fan. Based on the fan air volume calculated based on the heat exchange amount calculation means for calculating the heat exchange amount in the air-cooled heat exchanger, and based on the heat exchange amount and the power consumption of the pump and the fan, the unit consumption A coefficient of performance calculating means for calculating a coefficient of performance representing the cooling capacity per electric power, and based on the calculated coefficient of performance, maintaining the current rotation speed or increasing / decreasing the fan speed, or operating the outside air heat exchange system Operation control means for stopping.

  In the outside-air-use air conditioning system having the above-described configuration, for example, the control device can perform heat exchange amount and fan power consumption according to the virtual fan rotation speed based on the virtual fan rotation speed obtained by decreasing or increasing the fan rotation speed. And an estimated performance coefficient calculating means for estimating and calculating the performance coefficient according to the virtual fan rotational speed based on the estimated heat exchange amount and fan power consumption and the pump power consumption. The operation control means compares the performance coefficient calculated by the performance coefficient calculation means with the estimated performance coefficient estimated by the estimated performance coefficient calculation means, and based on the magnitude relationship between the two, Fan rotation speed increase / decrease determining means for determining whether to increase, decrease, or maintain the current state is provided.

Further, for example, the operation control means increases or decreases the fan rotation speed so that the coefficient of performance becomes substantially maximum.
In the outside air-conditioning air conditioning system having the above configuration, for example, the operation control unit compares the calculated coefficient of performance with a predetermined threshold value, and the coefficient of performance is less than the threshold value. If it does, the fan is stopped. This is, for example, the coefficient of performance of the air conditioning system alone by the refrigeration cycle, which is calculated in advance.

  If the coefficient of performance of the outside air heat exchange system is worse than the coefficient of performance of the air-conditioning system alone with the refrigeration cycle, there is no point in operating the outside air heat exchange system. Improve the coefficient of performance of the entire air conditioning system.

  According to the outside air utilization air conditioning system, the outside air heat exchange system, and the like of the present invention, the coefficient of performance is calculated based on the heat exchange amount and power consumption with the outside air in the outside air heat exchange system, and the outside air is calculated based on the coefficient of performance. By controlling the fan rotation speed of the heat exchange system, if the coefficient of performance falls below a predetermined threshold, the outside air heat exchange system is stopped, allowing operation at maximum efficiency in any outside air condition, and energy saving. I can plan.

It is a schematic block diagram of an outside air utilization air-conditioning system. It is a detailed block diagram of an outside air heat exchange system. It is a process flowchart figure of a control apparatus. It is a figure which shows the relationship between outside temperature and a coefficient of performance. It is a figure which shows the relationship between the fan rotation speed and a coefficient of performance / fan power in an external air heat exchange system.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic configuration diagram of an outside air-use air conditioning system to which the present technique is applied.
The schematic configuration shown in the drawing may be regarded as an existing configuration, and will be briefly described here.

  Also, in the description of the embodiment, the above-described general vapor compression type air-conditioning system using a refrigeration cycle is simplified to “air-conditioning system using refrigeration cycle”, “general air-conditioning system”, etc. It may be noted.

  In FIG. 1, a plurality of (multiple) server devices and the like are installed in a server room that is an air conditioning target. As described above, the operating server device may be regarded as a heating element, and if it is not cooled, the server device becomes hot and causes a failure of the server device. The same applies to other seasons such as winter as well as summer, and basically cooling is required throughout the year.

  In the illustrated example, the air handling unit 1 that is an indoor unit in a general air conditioning system generates cold air, sends the cold air to the underfloor space, and supplies the cold air to the server room via the underfloor space (illustrated). Server room air supply). The cool air supplied to the server room rises in temperature by being cooled by the server device, becomes warm air, rises, and flows out of the server room.

  Here, in the illustrated example, an air-conditioning room is provided in the building (building), and the air handling unit 1 and the server room are provided in the air-conditioning room. This space is called an air conditioning room. Therefore, it can be said that warm air (return air) flowing out from the server room flows into the air-conditioned room.

  In the air conditioning room, an air handling unit 1 and a heat exchanger 12 are provided as shown. In the case of only a general air conditioning system, warm air (server room return air; return air) flowing into the air conditioning chamber flows into the air handling unit 1 and is cooled inside the air handling unit 1. Will be discharged.

  Moreover, in the example of illustration, about the structure of the air-conditioning system by the said refrigerating cycle, only the air handling unit 1 and the refrigerant | coolant pipe | tube 2 which are the parts are shown, About other structures (a compressor, a condenser, an expansion valve, etc.). Is omitted. The air handling unit 1 includes an evaporator 1a, a fan 1b for intake of return air and exhaust of cold air, and the like as described above. The refrigerant pipe 2 is connected to the evaporator 1a, the compressor (not shown), the condenser, the expansion valve, and the like, and circulates the refrigerant through these components.

  In addition, the structure of the air-conditioning system by the said refrigerating cycle is not restricted to said example. For example, cold water is used as the refrigerant, and the configuration of the reference numeral 1a is not limited to the evaporator, but may be a heat exchanger that performs heat exchange between cold water and air. In this example, a cooling tower or the like is often provided outdoors instead of a condenser or the like.

  In the case of an outside air-use air conditioning system, as already described, an outside air heat exchange system is further provided in addition to the general air conditioning system. The outside air heat exchange system includes an air-cooled heat exchanger 11, a heat exchanger 12, a pump 13, a pipe 14, and the like illustrated. The details of the outdoor air heat exchange system will be described later with reference to FIG. 2, and only a brief description will be given here.

  The air-cooled heat exchanger 11 and the heat exchanger 12 are connected to a pipe 14, and a coolant (such as water) is circulated through the pipe 14. A power source for circulating the coolant is a pump 13 provided at an arbitrary position on the pipe 14.

  The air-cooling heat exchanger 11 is provided outdoors, and allows the outside air to pass through to exchange heat between the outside air and the coolant. In the air-cooled heat exchanger 11, a fan 11b for taking in and exhausting outside air is provided.

  On the other hand, the heat exchanger 12 is provided indoors (and thus may be referred to as the indoor heat exchanger 12), and by passing the return air (warm air), the heat of the return air and the coolant is passed. Let the exchange take place. The heat exchanger 12 is provided on the upstream side (front stage) of the air handling unit 1 with respect to the warm air flow. Thus, warm air (return air) that has flowed into the air-conditioned room from the server room first passes through the heat exchanger 12 and then flows into the air handling unit 1.

  The heat exchanger 12 is supplied with the cooling liquid cooled (basically) by heat exchange with the outside air in the air-cooling heat exchanger 11, and heat exchange between the cooling liquid and the return air is performed. And (basically) the return air is cooled by the coolant and the temperature drops. How much the temperature is lowered depends on the outside air temperature, the air volume, etc. as described above.

  The coolant whose temperature has risen (basically) by heat exchange with the return air in the heat exchanger 12 is cooled (basically) by heat exchange with the outside air again in the air-cooling heat exchanger 11. become.

  In addition, the heat exchanger 12 includes a heat exchanger body 12a, a fan 12b, and the like as illustrated. The pipe 14 is connected to a heat exchanger body 12a, and heat exchange is performed between the coolant and the return air through the heat exchanger body 12a. In addition, the fan 12b forms an air flow in which the return air flows into the heat exchanger 12 and is discharged toward the air handling unit 1.

  The power consumption in the outside air heat exchange system may be considered as the total power consumption of the fan 12b of the heat exchanger 12, the pump 13, and the fan 11b described later of the air-cooled heat exchanger 11.

  As described above, the return air first passes through the heat exchanger 12 and is cooled (basically) by heat exchange with the cooling liquid, so that the temperature decreases. Therefore, the return air whose temperature has been lowered flows into the air handling unit 1. Therefore, the burden for generating cold air at a predetermined temperature (set temperature) in the air handling unit 1 is reduced, and energy saving can be achieved.

  However, as already described, when the outside air temperature becomes higher than a certain level, the outside heat exchange system substantially does not function. In addition, since there is power consumption for the operation of the outside air heat exchange system, there is no point in operating the outside air heat exchange system unless a function (cooling of return air) more than this power consumption is performed. For example, if the outside air volume is increased by increasing the number of rotations of the fan 11a of the air-cooling heat exchanger 11, the cooling capacity increases, but at the same time, the fan power also increases. Therefore, it is desired to perform control so that the coefficient of performance (COP) (= cooling capacity per unit power consumption (heat exchange amount)), which is an index of cooling efficiency, is substantially optimal.

Therefore, in this method, in the outside air heat exchange system, for example, the configuration shown in FIG. 2 is used, and control by the flowchart processing shown in FIG. 3 is executed.
First, the detailed configuration of the outdoor air heat exchange system will be described with reference to FIG.

  In FIG. 2, the air-cooled heat exchanger 11 has a heat exchanger body 11a, a fan 11b, and the like. The heat exchanger body 11a is connected to the pipe 14, and the coolant flows through the heat exchanger body 11a. Further, as shown in the figure, the outside air is taken into the casing of the air-cooled heat exchanger 11 (supplied) by the fan 11b, and the outside air passes through the heat exchanger body 11a. Thereby, heat exchange is performed between the outside air and the coolant in the heat exchanger body 11a, and the coolant is basically cooled by the outside air (cold air). Thus, the outside air rises in temperature and is exhausted.

  Here, as shown in FIG. 2, a thermometer 21 and a thermometer 22 are provided for the air-cooled heat exchanger 11. The thermometer 21 is a thermometer that measures the temperature (referred to as cold air temperature Ti) at the time of intake (supply) of the outside air. The thermometer 22 is a thermometer that measures the temperature during exhaust of the outside air (referred to as exhaust temperature To). Further, a power meter 23 for measuring the power consumption of the pump 13 provided on the pipe 14 and a power meter 24 for measuring the power consumption of the fan 11b are further provided. Furthermore, a rotation speed control device 25 that controls the rotation of the fan 11b and a control device 30 that controls the entire outside air heat exchange system are provided.

The control device 30 includes a computing unit 31, an input interface 32, an output interface 33, and the like.
The computing unit 31 is an arithmetic processing unit having a CPU, a memory, and the like. A predetermined application program and the like are stored in advance in the memory (nonvolatile memory), and the CPU controls the entire outside air heat exchange system by reading and executing the application program from the memory. Here, in particular, the processing of the flowchart shown in FIG. 3 to be described later is executed.

  The computing unit 31 is connected to the cold air temperature Ti and the exhaust gas temperature To measured by the thermometer 21 and the thermometer 22 and the power consumption of the pump 13 and the fan 11b measured by the power meters 23 and 24 via the input interface 32. Enter etc. Further, the computing unit 31 transmits a control signal to the rotational speed control device 25 via the output interface 33, thereby causing the rotational speed control device 25 to control the rotational speed of the fan 11b (instructed rotational speed). n).

Hereinafter, an example of processing executed by the control device 30 (the arithmetic unit 31) will be described with reference to the flowchart of FIG.
The process in FIG. 3 is executed at predetermined intervals, for example.

  First, the cold air temperature To and the exhaust gas temperature Ti measured by the thermometers 21 and 22 are acquired (step S11). Then, the air temperature difference Ts is calculated by calculating “air temperature difference Ts = exhaust temperature To−cold air temperature Ti” (step S12).

Subsequently, the fan air volume Q of the fan 11b is calculated based on the fan rotation speed n of the fan 11b (step S13). As is well known, the square of the fan rotational speed n and the air volume Q are in a proportional relationship (n ² ∝Q), so an arbitrary coefficient α (for example, a catalog value of a product) is used. Thus, the fan air volume Q of the fan 11b is calculated by “Q = αn ² ”. Here, it is assumed that the rotation speed of the fan 11b is as instructed above. However, the present invention is not limited to this example. For example, a sensor for detecting the rotation speed of the fan 11b is provided. You may make it acquire the measured value of.

  Next, a heat exchange amount E by the air-cooled heat exchanger 11 (the heat exchanger body 11a) is obtained from the air temperature difference Ts and the fan airflow rate Q obtained in steps S12 and S13 (step S14). Here, the following relational expressions are known for the exhaust temperature To, the cold air temperature Ti, the fan air volume Q, and the heat exchange amount E.

To = Ti + {E / (Q · Cp)}
Cp is specific heat (for example, constant pressure specific heat of air).
Therefore, the following calculation formula (Equation (1)) for the heat exchange amount E is obtained from this equation.

E = (To−Ti) × (Q · Cp) = Ts × (Q · Cp) (1) Therefore, using the air temperature difference Ts and the fan airflow Q obtained in steps S12 and S13, The heat exchange amount E by the air-cooled heat exchanger 11 (its heat exchanger body 11a) can be calculated by the above equation (1). Note that the value of Cp is preset.

Subsequently, the fan power P _fan and the pump power P _pomp are measured (step S15). With respect to the pump power, the power consumption of the pump 13 measured by the power meter 23 is acquired and used as the pump power P _pomp . Similarly, regarding the fan power, the power consumption of the fan 11b measured by the power meter 24 is acquired, and this is set as the fan power P _fan . That is, in this example, the fan power P _fan means the power consumption of the fan 11b, and the pump power P _pomp means the power consumption of the pump 13.

Based on the heat exchange amount E calculated in step S14 and the fan power P _fan and pump power P _pomp measured in step S15, the coefficient of performance COP is calculated by the following equation (2) (step S16).

COP = E / (P _fan + P _pomp ) (2) The coefficient of performance COP based on the actual measurement value in the present state was obtained as described above. In addition, this shall be called measurement performance coefficient COP and shall distinguish with estimated performance coefficient COP 'mentioned later.

Subsequently, a coefficient of performance COP (estimated coefficient of performance COP ′) corresponding to the estimated air volume and power of the fan 11b is obtained by the following steps S17 to S19.
First, an estimation calculation of the fan air volume and fan power of the fan 11b when the rotational speed of the fan 11b of the air-cooling heat exchanger 11 is reduced is performed (step S17). In this example, the estimation calculation when the rotation speed is reduced is performed. However, the estimation calculation is not limited to this example, and the estimation calculation may be performed when the rotation speed is increased.

Regarding the process of step S17, the number of rotations of the fan 11b is reduced by an arbitrary fixed value (= m) set in advance (n ′ = nm). Then, using this estimated rotational speed (virtual fan rotational speed) n ′, the fan at the virtual fan rotational speed n ′ is substantially the same as in the case of the actual rotational speed value n (calculation formula “Q = αn ² ”). The estimated fan air volume Q ′ of 11b is obtained by the following equation.

Q ′ = αn ′ ²
Further, regarding the fan power, an actual measurement value is used in step S15, but here an estimation calculation is performed. That is, since the fan power (power consumption) is proportional to the cube of the fan rotation speed, the fan 11b at the virtual fan rotation speed n ′ is expressed by the following equation (3) using an arbitrary coefficient β set in advance. The fan power (power consumption) is estimated and calculated.

Fan power P ′ _fan = βn ′ ³ (3) In this way, “power consumption of the fan 11b when the rotation speed n ′ is reduced by reducing the rotation speed of the fan 11b of the air-cooling heat exchanger 11”. The estimated value of "" (estimated fan power _P'fan ) is obtained by the above equation (3).

Note that the values of the coefficients α and β are appropriately determined by the developer, for example, through experiments, but are not limited to this example.
Subsequently, the estimated heat exchange amount E ′ is calculated by the above equation (1) using the estimated fan air volume Q ′ obtained in step S17 (step S18). Note that this is calculated by replacing Q in the above equation (1) with Q ′. That is, according to the following equation (1) ′, the estimated heat exchange amount E ′ (the air cooling heat exchanger 11 (its heat) when the rotation number n ′ is reduced by reducing the rotation number of the fan 11b of the air cooling heat exchanger 11). The amount of heat exchange by the exchanger body 11a) is calculated. Here, it is assumed that Ts does not change (as shown in FIG. 5, Ts hardly changes when the rotational speed is slightly increased or decreased).

E ′ = Ts × Q ′ · Cp (1) ′ Formula However, the present invention is not limited to the above example. As described above, as shown in FIG. 5, Ts does not change much when the fan rotation speed (air volume) is slightly increased or decreased, but still changes. Therefore, in order to obtain the estimated heat exchange amount E ′ more accurately, the estimated heat exchange amount E ′ may be calculated as described below.

  That is, first, as described above, the air temperature difference Ts changes in accordance with the change in the air volume Q (Q → Q ′). However, since the change amount of the air temperature difference is not known here, it is considered to obtain the estimated heat exchange amount E ′ more accurately by using the air temperature difference Ts without using the change amount.

Here, since it can be considered that the heat exchange amount is in a proportional relationship in a certain air flow range, using the proportionality coefficient γ obtained in advance by experiments or the like,
E ′ / E = γ × (Q ′ / Q)
Will hold.

Substituting the above equation (1) into this, that is, substituting E = Ts × (Q · Cp), the following equation (1) ”is obtained.
E ′ = E × γ × (Q ′ / Q)
= Γ × Ts × (Q ′ × Cp) (1) ”Expression As described above, the expression (1)” is obtained by multiplying the expression (1) ′ by the proportional coefficient γ (on the right side). It becomes. The above expression (1) "may be used in place of the above expression (1) '. In this description, the expression"(1)'"includes the above expression (1)". You may consider it included.

Based on the estimated heat exchange amount E ′, the estimated fan power P ′ _fan, and the pump power P _pomp , it is estimated by the same calculation formula (the following formula (2) ′) as the above formula (2). A coefficient of performance COP ′ is calculated (step S19). Since the pump power is not changed, the pump power P _pomp based on the actually measured value is used as it is.

COP ′ = E ′ / (P _fan ′ + P _pomp ) (2) ′ Formula After the measurement performance coefficient COP and the estimated performance coefficient COP ′ are calculated by the above processing, the following formula (4) is first given. To calculate the coefficient of performance difference value COP ″ (step S20).

COP "= estimated coefficient of performance COP'-measured coefficient of performance COP (4) Then, it is determined whether or not the difference value COP" is "0" (step S21), and the difference value COP "is" 0 ". If it is' (step S21, YES), the rotational speed of the fan 11b is not increased / decreased (to maintain the current state), and the process proceeds to step S25 described later.

  On the other hand, if the difference value COP ″ is not “0” (step S21, NO), first, it is determined whether the difference value COP ″ is a positive value or a negative value (step S22). . When the difference value COP ″ is a positive value (step S22, YES), the fan rotational speed is decreased (step S23). This is decreased by a predetermined amount m set in advance. On the other hand, when the difference value COP ″ is a negative value (step S22, NO), the fan rotation number is increased (step S24). This is increased by a predetermined amount m (n = n + m). The fan that increases or decreases the rotational speed is the fan 11 b of the air-cooled heat exchanger 11.

Here, the process of the said step S20-step S24 is demonstrated with reference to FIG.
FIG. 5 is a diagram showing the relationship between the fan rotation speed and the coefficient of performance / fan power in the outside air heat exchange system.

  In FIG. 5, the horizontal axis represents the fan rotation speed, and in this description, the rotation speed of the fan 11b is meant. And the relationship between fan rotation speed, fan power, and a coefficient of performance is mainly shown.

  In FIG. 5, for further reference, the relationship between the fan speed and the exhaust gas temperature / cold air temperature (whichever is the dry bulb temperature) is also shown (both are indicated by a one-dot chain line). In brief, the cold air (dry bulb) temperature does not change depending on the fan rotation speed and is constant as shown in the figure, while the exhaust (dry bulb) temperature is large at the fan rotation speed. As it becomes, it gradually decreases.

In FIG. 5, the relationship between the fan speed and the coefficient of performance is indicated by a thick solid line, and the relationship between the fan speed and the fan power is indicated by a thin solid line.
As indicated by the thin solid line (and of course), the fan power increases as the fan speed increases.

  On the other hand, as indicated by the thick solid line, the coefficient of performance decreases as the fan rotational speed becomes larger than the rotational speed F1, with the peak at the fan rotational speed (F1 in the figure). . When the fan rotation speed becomes equal to or greater than a certain value (F2 in the drawing), the coefficient of performance becomes less than the lower limit set value (described later, a predetermined threshold value set in advance = 'r', etc.), and will be described later in step S27. Will stop operation.

  Similarly, in the region where the fan rotation speed is smaller than the rotation speed F1, as shown in the figure, the value of the coefficient of performance decreases as the fan rotation speed decreases. When the fan rotation speed becomes less than a certain value (F3 in the drawing), the coefficient of performance becomes less than the lower limit set value (predetermined threshold = 'r'), and the operation is stopped in step S27 described later. .

  The process of steps S20 to S24 is to make the coefficient of performance as close as possible to the coefficient of performance (peak value) when the fan rotation speed is a predetermined rotation speed (F1 in the drawing). And even if it is near the peak value, if it is less than the lower limit set value, the operation is stopped in step S27.

  First, in the present example, from the characteristics shown in FIG. 5, it is assumed that the coefficient of performance hardly changes even if the rotational speed is slightly increased or decreased near the peak value. Accordingly, if the determination in step S21 is YES, that is, if the difference value of the coefficient of performance is “0” (that is, the coefficient of performance does not change) when the rotational speed is decreased, the fan rotational speed is the above rotation. It is assumed that it is in the vicinity of number F1 (the coefficient of performance is in the vicinity of the peak value). In this case, since it is considered that there is no need to increase or decrease the rotational speed (because it is considered to be almost the best state when judging by the coefficient of performance), as described above, when the determination in step S21 is YES, The rotation speed of the fan 11b is not changed.

Note that the determination in step S21 is not limited to a case where the value is completely “0”, and may be determined as YES if it is close to “0” to some extent by including a predetermined margin.
In FIG. 5, the current fan speed n is assumed to be F4 shown in the figure, and the measurement performance coefficient COP and fan power P _fan are shown. In step S17, the fan speed is reduced and the estimated speed n ′. = F5 and the estimated coefficient of performance in the case of COP ', estimated fan power P' indicates a _fan. In the illustrated example, since the estimated performance coefficient COP ′ is larger than the measurement performance coefficient COP, the determination in step S22 is YES, and the rotational speed is decreased in step S23. In this case, the process of step S23 may be considered to mean that the fan rotational speed n is set to the estimated rotational speed n ′ (= F5). If this is described as “n = n−m” using m described above, the processing in step S24 may be considered as “n = n + m”.

  In addition, if the determination in step S22 is NO, it is considered that the current rotational speed n is smaller than the predetermined rotational speed F1 (the left region in the figure). Therefore, in this case, it can be expected that the coefficient of performance approaches the peak value (the rotation speed approaches F1) by increasing the rotation speed in step S24.

  As described above, when it is estimated that the coefficient of performance increases (results improve) by reducing the rotation speed of the fan 11b, the coefficient of performance is improved by reducing the rotation speed (peak value). ). On the contrary, when it is estimated that the coefficient of performance is reduced (results deteriorated) by decreasing the rotational speed of the fan 11b, the coefficient of performance is improved by increasing the rotational speed.

As already described, the process of step S17 may be an increase in the number of rotations instead of a decrease in the number of rotations. Also in this case, the determination in step S22 is merely “difference value <0?” Instead of “difference value> 0?”, And the meaning of the process itself does not change. That is,
When it is estimated that the coefficient of performance is increased (the result is improved) by increasing the rotation speed of the fan 11b, the coefficient of performance is improved by increasing the rotation speed. On the contrary, when it is estimated that the coefficient of performance is reduced (the result is deteriorated) by increasing the rotational speed of the fan 11b, the performance coefficient is improved by decreasing the rotational speed.

  Here, by repeating the above processing, it can be expected that the fan speed gradually approaches F1. However, the fan speed is in the vicinity of F1 and the coefficient of performance is in the vicinity of the target value (near the maximum value). However, the coefficient of performance may be less than the “performance coefficient lower limit setting value” (“r” described later) shown in the figure. The graph of the coefficient of performance shown is in a state where the outside air temperature is not high. When the outside air temperature increases, the graph of the coefficient of performance decreases as a whole. "Can occur. This corresponds to a state of the outside air temperature Tk or higher in FIG. 4 described later, and will be described in detail later with reference to FIG.

  As a result, by repeating the above-described processing a plurality of times, the fan rotation speed is in the vicinity of F1, and the coefficient of performance is in the vicinity of the target value (near the maximum value). It is determined whether or not the value is less than “value”.

  First, if the determination in step S21 is YES, or after executing any of the processes in steps S23 and S24, the processes in steps S11 to S24 are executed a preset number of times (S times). It is determined whether or not (step S25). If the number of executions s of steps S11 to S24 is less than a predetermined number (S times), the number of executions s is incremented by +1 and the process returns to step S11, and the processing of steps S11 to S24 is performed again. The determination in step S25 is performed again. The predetermined number of times (S times) may be arbitrarily determined and set. For example, about 10 to several tens of times may be considered.

  If the determination in step S25 is YES, the process proceeds to step S26. Note that the present invention is not limited to the above example. For example, if the determination in step S21 is YES, the process may directly proceed to step S26.

  In step S26, it is checked whether or not the measurement performance coefficient COP is less than a predetermined lower limit setting value (step S26). If the measurement performance coefficient COP is less than the predetermined lower limit setting value (COP <lower limit setting value) (step S26, YES), the fan 11b and the like are stopped (step S27), and this process is terminated. The process of step S27 stops all the fans 11b, the fans 12b, and the pump 13, for example, and this substantially means that the outside air heat exchange system is stopped. On the other hand, if the measurement performance coefficient COP is equal to or greater than the predetermined lower limit setting value (COP ≧ lower limit setting value) (step S26, NO), the number of executions s is reset to “1”, and then this process is terminated. .

  As already described, the coefficient of performance graph in FIG. 5 may be a graph that is less than the lower limit setting value even when the outside air temperature is high. Then, the fan 11b and the like are stopped to optimize the coefficient of performance of the entire outside air-use air conditioning system.

  Incidentally, for example, the outside air temperature (measured temperature of the thermometer 21, etc.) at the time of the operation stop of the outside air heat exchange system is stored, and the measured temperature of the thermometer 21 is periodically acquired even after the operation is stopped. When the air temperature is lower than a predetermined amount by more than a predetermined amount (for example, when the outside air temperature falls by 3 ° C. or more; for example, when the outside air temperature at the time of operation stop is 30 ° C. and the outside air temperature becomes less than 27 ° C.) Operation may be resumed. After the operation is restarted, for example, the process of FIG.

Note that the power consumption of the outside air heat exchange system includes the power consumption of the fan 12b. Therefore, a power meter for measuring the power consumption of the fan 12b may be further provided, and the fan power P _fan may be calculated by “power consumption of the fan 11b + power consumption of the fan 12b”. In this example, the estimated fan power P ′ _fan may be “estimated power consumption of the fan 11b + power consumption of the fan 12b” or the like (the rotational speed of the fan 12b is not changed).

Here, the processes in steps S25 to S27 will be described with reference to FIG.
In FIG. 4, the horizontal axis represents the outside air temperature, and the vertical axis represents the COP, which shows the relationship between the outside air temperature and the COP. The outside air temperature-COP relationship of a general air conditioning system such as the air handling unit 1 is indicated by a thick solid line in the figure. Further, the outside air temperature-COP relationship of the outside air heat exchange system is indicated by a thin solid line on the figure.

  Here, in the figure, the thin solid line is a dotted line in the middle (in a region where the outside air temperature is equal to or higher than a certain value), and this shows a case where the process of step S27 is not performed. That is, as shown in the drawing, the outside air temperature and the COP are in an inversely proportional relationship with respect to the outside heat exchange system, and the COP decreases as the outside temperature increases. On the other hand, as shown in the figure, regarding a general air conditioning system, the COP is hardly influenced by the outside air temperature, and the value of the COP is substantially constant (COP = r). Note that the value of r may be calculated in advance by a developer or the like based on the measurement / calculation results of the heat exchange amount and power consumption of a general air conditioning system in a state where the outside air heat exchange system is stopped. .

  Accordingly, when the outside air temperature is relatively low (less than the illustrated outside air temperature Tk), the COP of the outside air heat exchange system is larger than the above 'r', but the outside air temperature is relatively high (over the outside air temperature Tk illustrated in the figure). ), The COP of the outside air heat exchange system is smaller than 'r'. Further, the COP of the entire outside air use air conditioning system (general air conditioning system + outside air heat exchange system) is, for example, indicated by a one-dot chain line in the figure. That is, in a state where the temperature is equal to or higher than the outside air temperature Tk, the COP of the entire outside air-use air conditioning system is lower than the COP when the general air conditioning system is operated alone. This makes no sense to operate the outdoor air heat exchange system.

  Thus, in this method, for example, by setting the above 'r' as the lower limit set value used in step S26 (lower limit set value = r), the outside air temperature is relatively high (above the outside air temperature Tk in the drawing). In some cases, the outside air heat exchange system is put into an operation stop state to prevent the COP from decreasing and maximize the coefficient of performance of the entire outside air-conditioning air conditioning system.

  As described above, according to the outside air-conditioning system to which this method is applied, the outside air heat exchange system, etc., the coefficient of performance is calculated based on the heat exchange amount and power consumption with the outside air in the outside air heat exchange system. By controlling the air volume of the fan of the outside air heat exchange system based on this coefficient of performance, and further stopping the outside air heat exchange system when the coefficient of performance falls below a predetermined set value, it is almost the maximum in any outside air condition. Operation is possible with efficiency and energy saving can be achieved.

DESCRIPTION OF SYMBOLS 1 Air handling unit 1a Evaporator 1b Fan 2 Refrigerant tube 11 Air cooling heat exchanger 11a Heat exchanger main body 11b Fan 12 Heat exchanger 12a Heat exchanger main body 12b Fan 13 Pump 14 Piping 21 Thermometer 22 Thermometer 23 Wattmeter 24 Electric power Total 30 Controller 31 Operation unit 32 Input interface 33 Output interface

Claims (7)

Cooling liquid is circulated through an air conditioning system using a refrigeration cycle having an indoor unit that generates cold air, an indoor heat exchanger provided in front of the indoor unit, and an air-cooled heat exchanger provided outdoors, and the indoor heat exchange An outside air-conditioning air-conditioning system having an external air heat exchange system for performing heat exchange between the cooling liquid and indoor warm air in a cooler and performing heat exchange between the cooling liquid and outside air in the air-cooled heat exchanger. ,
Power consumption measuring means for measuring power consumption of a pump for circulating the coolant and power consumption of a fan of the air-cooled heat exchanger;
A temperature measuring means for measuring the supply air temperature and exhaust temperature of the outside air passing through the air-cooling heat exchanger;
A controller that inputs each of the power consumption measured by the power consumption measuring means, inputs the supply air temperature and exhaust temperature measured by the temperature measuring means, and controls the rotational speed of the fan;
The controller is
A heat exchange amount calculating means for calculating a heat exchange amount in the air-cooled heat exchanger based on a temperature difference between the supply air temperature and the exhaust temperature and a fan air volume calculated based on the rotational speed of the fan;
A coefficient of performance calculation means for calculating a coefficient of performance representing the cooling capacity per unit power consumption based on the heat exchange amount and the power consumption of the pump and the fan;
Based on the calculated coefficient of performance, operation control means for maintaining the current rotational speed of the fan or increasing / decreasing the fan speed, or stopping the outside air heat exchange system;
An air-conditioning system using outside air characterized by comprising: The controller is
Based on the virtual fan rotation speed obtained by decreasing or increasing the fan rotation speed, the heat exchange amount and fan power consumption corresponding to the virtual fan rotation speed are estimated and calculated, and the estimated heat exchange amount and fan power consumption are calculated. And an estimated performance coefficient calculating means for estimating and calculating the performance coefficient according to the virtual fan speed based on the pump power consumption,
The operation control means includes
The performance coefficient calculated by the performance coefficient calculation means is compared with the estimated performance coefficient estimated by the estimated performance coefficient calculation means, and the fan speed is increased or decreased based on the magnitude relationship between the two. 2. An air-conditioning system using outside air according to claim 1, further comprising a fan rotation speed increase / decrease determining means for determining whether to maintain the current state.   The outside air-conditioning system according to claim 2, wherein the operation control unit increases or decreases the fan rotation speed so that the coefficient of performance becomes substantially maximum.   When the virtual fan rotation speed is a decrease of the fan rotation speed, the operation control means increases the fan rotation speed when the estimated performance coefficient is smaller than the performance coefficient, 4. The outside-air-use air conditioning system according to claim 2, wherein when the estimated coefficient of performance is larger than the coefficient of performance, the fan speed is decreased.   The operation control means compares the calculated coefficient of performance with a predetermined threshold value set in advance, and stops the operation of the fan when the coefficient of performance falls below the threshold value. The air-conditioning system using outside air according to any one of claims 1 to 4.   6. The outdoor air-conditioning air conditioning system according to claim 5, wherein the threshold value is a coefficient of performance calculated in advance for the air conditioning system alone based on the refrigeration cycle. A coolant is circulated through an indoor heat exchanger provided upstream of an indoor unit in an air conditioning system using a refrigeration cycle, and an air-cooled heat exchanger provided outdoors, and the coolant and the indoor warm air are circulated in the indoor heat exchanger. An outside air heat exchange system for performing heat exchange between the coolant and outside air in the air-cooled heat exchanger,
Power consumption measuring means for measuring power consumption of a pump for circulating the coolant and power consumption of a fan of the air-cooled heat exchanger;
A temperature measuring means for measuring the supply air temperature and exhaust temperature of the outside air passing through the air-cooling heat exchanger;
A controller that inputs each of the power consumption measured by the power consumption measuring means, inputs the supply air temperature and exhaust temperature measured by the temperature measuring means, and controls the rotational speed of the fan;
The controller is
A heat exchange amount calculating means for calculating a heat exchange amount in the air-cooled heat exchanger based on a temperature difference between the supply air temperature and the exhaust temperature and a fan air volume calculated based on the rotational speed of the fan;
A coefficient of performance calculation means for calculating a coefficient of performance representing the cooling capacity per unit power consumption based on the heat exchange amount and the power consumption of the pump and the fan;
Based on the calculated coefficient of performance, operation control means for maintaining the current rotational speed of the fan or increasing / decreasing the fan speed, or stopping the outside air heat exchange system;
An outdoor air heat exchange system characterized by comprising: