JP4994754B2 - Heat source system - Google Patents

Description

  The present invention relates to a heat source system that achieves high efficiency by improving the COP (coefficient of performance) of a heat source system including a refrigerator, a cooling tower, a cooling water pump, a cooling water pump, and the like.

  Conventionally, a heat source system has been used in various facilities such as office buildings for heat loads such as air conditioning equipment. The heat source system includes a refrigerator, a cooling tower, and a cooling water pump in a cooling water system, and the cooling water pump circulates the cooling water from the refrigerator to the cooling tower in the cooling water pipe, and the condenser of the refrigerator It is the structure which cools the cooling water which raised the temperature in said cooling tower. Moreover, in the cold water system provided with the heat load, the cold water in the cold water pipe is cooled by the evaporator of the refrigerator and circulated to the heat load.

  In such a heat source system, it is known that if the cooling water temperature is lowered, the efficiency of the refrigerator is improved. Usually, however, in the intermediate period (partial load) other than the maximum load (peak time) When the outside air temperature becomes low, the cooling water temperature is lowered accordingly.

  Therefore, it is conceivable to improve the efficiency of the entire heat source system by lowering the cooling water temperature of the cooling water system at the peak load in summer, but for this purpose, the power of the cooling tower blower fan is increased or the same configuration is used. It has been proposed that a plurality of cooling towers are juxtaposed to improve the cooling capacity, thereby reducing the cooling water temperature and thereby improving the COP (coefficient of performance) of the refrigerator (Patent Document 1).

  Also, during peak loads, the cooling water temperature difference between the inlet temperature and outlet temperature of the refrigerator is operated at a cooling water flow rate of 5 ° C., and during partial loads, the power of the cooling water pump is reduced and controlled by an inverter. Thus, it has been proposed to reduce the flow rate of the cooling water and thereby reduce the power to improve the efficiency of the entire heat source system (Patent Document 2).

JP-A-2005-214608 JP-A-2005-257221

  By the way, in the technique of the above-mentioned Patent Document 1, the number of cooling towers is increased to increase the capacity of the cooling towers by about twice, and the condensation temperature of the turbo refrigerator is lowered to improve the COP of the refrigerator. If the number of cooling towers is increased, the power consumption of the cooling fan provided in each cooling tower is increased, and the power consumption of the cooling water system is increased. For this reason, there exists a subject that it does not necessarily lead to optimization of COP of a cooling water system.

  In the technique of Patent Document 2, the temperature difference between the cooling water inlet and the cooling water outlet of the compression refrigerator is changed according to the COP of the refrigerator, but there are many sensors and inverters in the heat source system. Therefore, there is a problem that the configuration and control of the heat source system are complicated and the design and operation are difficult.

  The present invention has been made in view of the above problems, and by increasing the heat exchange area between the outside air and the cooling water temperature without increasing the fan power of the cooling tower, the cooling water temperature of the cooling tower can be reduced annually. In order to realize such a temperature difference, the cooling water temperature difference between the inlet temperature and the outlet temperature of the refrigerator is set to be larger than the conventional temperature difference at the peak time. By operating at a constant flow rate throughout the year with a cooling water flow rate, a highly efficient heat source system with a simple structure is realized without the need for complicated control.

In order to solve the above problems, the present invention
First, a cooling water system composed of a cooling tower, a refrigerator, and a cooling water pump that circulates the cooling water by connecting between them with piping, and the cold water cooled by the refrigerator is loaded to the load side by the cold water pump In the heat source system consisting of the chilled water system to be supplied, the cooling tower increases the heat exchange area between the outside air and the cooling water without increasing the fan power of the cooling tower, so that the cooling water outlet temperature of the cooling tower can be increased throughout the year. The heat source system is characterized in that it is set to be lowered by about 1 ° C.

  The said refrigerator is a turbo refrigerator (compression type refrigerator), for example. With this configuration, the temperature can be set to about 1 ° C. lower than the conventional cooling water temperature (32 ° C. at the peak), for example, at the time of partial load as well as the summer peak. The COP (coefficient of performance) of the machine can be improved throughout the year. Further, since the cooling water temperature is reduced without increasing the power of the cooling fan of the cooling tower, the COP of the heat source system can be improved and efficient operation can be realized. The cooling water temperature difference of about 1 ° C. refers to a temperature that includes 1 ° C. and generally includes a range of 0.5 ° C. to 2.0 ° C.

  Second, the cooling water outlet temperature at the time of 100% load operation of the cooling tower is around 31 ° C., and is constituted by the heat source system according to the first aspect.

  If comprised in this way, the COP of a heat source system can be improved to the maximum by reducing the power consumption especially in the peak of summer. The vicinity of 31 ° C. of the cooling water inlet temperature refers to a temperature that includes 31 ° C. and generally includes a temperature range of 30 ° C. to the lower half of the 31 ° C. range.

  Third, the flow rate of the cooling water is determined so that the temperature difference between the cooling water inlet temperature and the cooling water outlet temperature of the refrigerator is close to 7 ° C. when the cooling tower and the refrigerator are operated at 100% load. In addition, the cooling water pump is configured to circulate a constant amount of cooling water with the determined flow rate through the cooling water system throughout the year. is there.

  If comprised in this way, when the cooling water inlet temperature will be 31 degreeC in the peak time of summer (at the time of a driving | operation of 100% load), for example, the temperature will rise to 38 degreeC in a refrigerator (temperature difference 7 degreeC). The refrigerator flows out and flows into the cooling tower, is cooled to 31 ° C. by the cooling tower, and flows into the refrigerator again by the cooling water pump. Therefore, the cooling water temperature difference of the refrigerator is kept at 7 ° C. at the peak of summer. In addition, since the cooling water flow rate is determined based on the cooling water temperature difference (7 ° C.) during the operation of the refrigerator at 100% load, the cooling water amount is smaller than the conventional cooling water temperature difference (5 ° C.). The flow rate can be adjusted, and a low-capacity cooling water pump can be used. In addition, the amount of heat generated by the refrigerator decreases at times other than the peak, but the temperature difference becomes small because the amount of cooling water maintains a constant flow rate. However, since the cooling water outlet temperature is lowered, the COP (coefficient of performance) of the refrigerator is improved. Therefore, efficient operation with low power consumption can be performed even at the time of partial load. The temperature difference of the cooling water in the vicinity of 7 ° C. means a temperature including 7 ° C. and a temperature difference generally including the range from the latter half of 6 ° C. to the lower half of 8 ° C.

  Fourth, the COP (coefficient of performance) of the heat source system is always the maximum throughout the year during the 100% load operation and the partial load operation of the cooling tower and the centrifugal chiller. It is comprised by the heat-source system in any one of -3.

  The heat source system according to the present invention improves the COP of the refrigerator by setting the cooling water temperature as low as about 1 ° C. throughout the year without increasing the fan power of the cooling tower.

  In addition, the heat source system according to the present invention sets the cooling water temperature difference of the refrigerator at the peak time larger than before, and circulates constant cooling water throughout the year with a cooling water flow rate smaller than before, It reduces the annual power consumption and enables efficient operation.

  Therefore, complicated operation such as rotation speed control by the inverter of the cooling water pump is not required, and efficient operation can be realized with a very simple configuration.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, the COP (coefficient of performance) in the system of the present invention refers to the COP of the cooling water system heat source system excluding the chilled water system chilled water pump (see formulas (5) and (6) described later).

  First, the basic configuration of the heat source system of the present invention will be described in detail with reference to FIG. The heat source system according to the present invention is a system used for air conditioning equipment such as a building, and includes a cooling tower 1 composed of cooling towers 1a to 1c, a turbo refrigerator (compression refrigerator) 2, the cooling tower 1 and the above. A cooling water pipe 3 that is piped between the cooling machine 2 and is composed of an outgoing pipe 3a and a return pipe 3b for the cooling machine, and installed in the cooling water pipe 3 between the cooling machine 2 and the cooling tower 1 A cooling water pump 4 that circulates cooling water therebetween, a chilled water pipe 5 that is connected to the refrigerator 2 and supplies cold water to the load side, and a chilled water pump 6 installed in the chilled water pipe 5. The system through which the cooling water circulates is called a cooling water system, and the system through which the chilled water circulates is called a cold water system. In each of the cooling towers 1a to 1c, 7a to 7c are cooling fans for introducing outside air, 8a to 8c are sprays for spraying the cooling water, 9 is cooling water, and cooling water inlets of these cooling towers 1a to 1c are provided. Are connected to the return pipe 3b, and the cooling water outlets of the cooling towers 1a to 1c are connected to the outgoing pipe 3a.

  In the turbo refrigerator 2, 10 is a condenser for liquefying the vaporized refrigerant, and the cooling water flows from the refrigerator inlet 12a through the condenser 10 to the return pipe 3b from the refrigerator outlet 12b. . 11 is an evaporator for vaporizing the liquefied refrigerant, and the cold water of the refrigerator 2 flows out from the cold water inlet 13a through the evaporator 11 to the cold water pipe 5 from the cold water outlet 13b. Reference numeral 14 denotes a compressor for compressing and vaporizing the liquefied refrigerant. 15a is a temperature sensor for measuring the cooling water inlet temperature of the turbo chiller 2, 15b is a temperature sensor for measuring the cooling water outlet temperature of the turbo chiller 2, and 16a is measuring the cooling water inlet temperature of the turbo chiller 2. The temperature sensor 16b is a temperature sensor for measuring the temperature of the chilled water outlet of the turbo chiller 2, and 17 is an operation unit for the turbo chiller 2. The temperature sensor 15a, 15b is displayed by a display unit (not shown). Output values, i.e., cooling water inlet temperature and cooling water outlet temperature, and output values of the temperature sensors 16a and 16b, i.e., cold water inlet temperature and cold water outlet temperature, etc. can be displayed. Although not shown, the heat source system includes a power panel for supplying power to each power unit and a control panel for performing various controls.

  In the heat source system having such a configuration, in the cooling water system, the cooling water flowing out from the cooling towers 1a to 1c flows into the turbo chiller 2 through the forward pipe 3a at a constant flow rate based on the capacity of the cooling water pump 4, The condenser 10 of the turbo chiller 2 absorbs the heat accompanying the liquefaction of the refrigerant, rises in temperature, flows out to the return pipe 3b, and further flows into the cooling towers 1a to 1c through the pipe 3. After being sprayed from the sprays 8a, 8b and 8c of the towers 1a to 1c and cooled by outside air in each cooling tower, each flows into the outgoing pipe 3a and is sent out to the refrigerator 2 by the cooling water pump 4.

  In the chilled water system, the chilled water whose temperature has risen due to the load is sent to the refrigerator 2 by the chilled water pump 6, and the temperature of the evaporator 11 of the refrigerator 2 is deprived of heat with the vaporization of the refrigerant. And flows out from the cold water outlet 13b of the refrigerator 2 through the cold water pipe 5 to the load side. It should be noted that the refrigerant in the turbo refrigerator 2 becomes a gas compressed by the compressor 14 and repeats the cycle of flowing into the condenser 10 again.

  In addition, in FIG. 1, 18 is a bypass valve connected between the said outgoing pipe 3a and the return pipe 3b, and when external temperature falls in the intermediate period when an air-conditioning load becomes small, and cooling water temperature falls, The bypass valve 18 is opened to bypass the cooling water in the return pipe 3b to the outgoing pipe 3a side, so that the cooling water inlet temperature does not fall below the lower limit value of the turbo chiller 2.

(A) Regarding COP (Coefficient of Performance) of Single Turbo Refrigerator In the heat source system configured as described above, first, the COP (coefficient of performance) of the turbo chiller alone, that is, “the turbo chiller with respect to the power consumption of the turbo chiller. Focus on the ratio of production heat. Here, the COP of the single centrifugal chiller is obtained by the following equation (1).
Turbo chiller COP = (Production heat of turbo chiller) / (Power consumption of turbo chiller)
.... (1)
Here, the production heat quantity of the turbo refrigerator is obtained by the following equation (2).
Production quantity of turbo refrigerator = {(cold water inlet temperature−cold water outlet temperature) × cold water flow rate}
... (2)
Further, the amount of heat dissipated from the cooling tower to the outside air is obtained by the equations (3) and (4).
Heat radiation from cooling tower = production heat of turbo chiller + power consumption of turbo chiller (3)
Heat release from cooling tower = {(cooling water outlet temperature−cooling water inlet temperature) × cooling water flow rate} · (4)

  FIG. 3 shows a COP (coefficient of performance) of a general inverter-controlled turbo chiller 2 used as the heat source system. The ordinate represents the COP and the horizontal axis represents the load factor. It shows the relationship between the load factor and the COP for each cooling water inlet temperature. From the figure, it can be seen that the COP of the centrifugal chiller improves as the cooling water temperature decreases as a whole. That is, it is predicted that the turbo chiller 2 can be operated more efficiently as the cooling water temperature is lower, and can contribute to the COP improvement of the heat source system throughout the year.

  Here, the cooling water inlet temperature of the turbo refrigerator 2 is determined by the design conditions of the cooling tower 1. Conventionally, the design condition of the cooling tower 1 is designed so that it can be operated at a cooling water inlet temperature of 37 ° C. and a cooling water outlet temperature of 32 ° C. at the peak of summer, that is, when the cooling tower 1 is 100% loaded. . Such a conventional general cooling tower is hereinafter referred to as “standard cooling tower”.

  Therefore, in order to improve the COP of the turbo chiller 2 and the heat source system, the cooling water inlet temperature of the turbo chiller 2 at the peak of the summer season is changed from the conventional 32 ° C. to around 31 ° C. (including a temperature range of approximately 31 ° C. We will consider reducing the temperature to 30 ° C to the temperature including the lower half of the range of 31 ° C (the same shall apply hereinafter), thereby improving the COP of the turbo refrigerator alone.

  In order to lower the cooling water inlet temperature of the turbo chiller 2 at the peak time by about 1 ° C. (a temperature including 1 ° C. and including a range of approximately 0.5 ° C. or more and 2.0 ° C. or less; the same applies hereinafter), the cooling tower 1 It is necessary to improve the cooling capacity. That is, the design conditions of the cooling tower 1 at the peak time (100% load) are, for example, an outside air temperature of 33.5 ° C. and an outside air wet bulb temperature of 27.5 ° C., and the cooling tower 1 at this time has a cooling water outlet temperature of around 31 ° C. The cooling water temperature is lowered by about 1 ° C. (or 1 ° C. or more) as compared to the conventional cooling water temperature so that it becomes (or 31 ° C. or less). As a result, according to the cooling tower 1 having such a cooling capacity, the cooling water temperature is reduced by about 1 ° C. throughout the year not only at the peak time but also at the partial load other than the peak time.

  At this time, in order to improve the cooling capacity of the cooling tower 1, it is considered to add a plurality of cooling towers 1 as described in the prior art or increase the power of the cooling fan of the cooling tower 1. However, in any case, the cooling fan power of the cooling tower 1 increases, and as a result, the power consumption of the cooling water system increases and the COP of the heat source system may be reduced. Therefore, the improvement of the cooling capacity of the cooling tower 1 increases the heat exchange area between the outside air and the cooling water from about 1.5 times to about 2 times without increasing the power of the cooling fan 7a and the like of the cooling tower 1. By doing. Hereinafter, by increasing the heat exchange area without increasing the power of the cooling fan in this way, the cooling water temperature is about 1 ° C. lower than the standard cooling tower throughout the year near the peak cooling water outlet temperature of 31 ° C. The cooling tower that achieves this is called a "high-performance cooling tower".

(B) Cooling Water Temperature Difference of Turbo Refrigerator Next, the inventors of the present invention pay attention to the cooling water inlet / outlet temperature difference of the turbo chiller 2 in studying further improvement of the COP of the heat source system. did.

  As described above, the conventional centrifugal chiller has a cooling water inlet temperature of 32 ° C. and a cooling water outlet temperature of 37 ° C., and is operated at a temperature difference of 5 ° C. Generally, the production heat quantity of the turbo chiller is 100%. With reference to the heat quantity Q produced at the time of load (summer peak), the reference heat quantity Q is designed to be produced at 100% load. Therefore, considering the time of 100% load (summer peak), the amount of heat Q to be produced and the power consumption of the centrifugal chiller are uniquely determined. From the above equations (2) and (4), the cooling water temperature difference When the flow rate is increased, the cooling water flow rate can be reduced.

  That is, by increasing the cooling water temperature difference, the COP of the turbo chiller 2 itself decreases, but instead the cooling water flow rate can be reduced, so that the power of the cooling water pump 4 can be reduced. And it is predicted that the reduction of the power of the cooling water pump 4 will lead to the reduction of the COP of the heat source system.

  Therefore, based on the above findings, the inventors made the following calculations for the heat source system shown in FIG. 1 when the standard cooling tower is used and when the high performance cooling tower is used. went.

(A) Condition 1 (when a standard cooling tower is used) (see FIG. 4 (a))
The standard type cooling tower was used as the cooling tower 1. Therefore, the cooling water outlet temperature of the cooling tower 1 at the peak time is 32 ° C., and the cooling water inlet temperature of the turbo refrigerator 2 is 32 ° C. The turbo chiller uses the heat quantity Q produced at peak time (100% load) and the heat quantity Qs radiated from the standard cooling tower (constant peak time) as reference values for the cooling water temperature of the turbo chiller 2 at the peak time. The cooling water flow rates when the differences were 5 ° C., 6 ° C., 7 ° C., 8 ° C., 9 ° C. and 10 ° C. were determined based on the above formulas (2) and (4). That is, the cooling water flow rate becomes Qs / 5, Qs / 6, Qs / 7, Qs / 8, Qs / 9, and Qs / 10 for each temperature difference.

  Then, it is assumed that a constant flow rate is circulated in the cooling water system for each temperature difference even during a year other than the peak using the cooling water pump 4 having a capacity capable of delivering these cooling water flow rates. And for every said cooling water temperature difference, the annual power consumption was computed about the load factor (after-mentioned) of three patterns of the following patterns AC.

(B) Condition 2 (when a high-performance cooling tower is used) (see FIG. 4B)
The high performance type cooling tower was used as the cooling tower 1. Therefore, the cooling water outlet temperature of the cooling tower 1 at the peak time is 31 ° C., the cooling water inlet temperature of the turbo refrigerator 2 is 31 ° C., and the cooling water temperature is set to be about 1 ° C. lower than the above condition 1 throughout the year. . The turbo chiller 2 cools the turbo chiller 2 at the peak time with the heat quantity Q produced at the peak time (100% load) and the heat quantity Qh radiated from the high performance type cooling tower (constant at the peak time) as reference values. Similarly, the cooling water flow rate when the water temperature difference was 5 ° C., 6 ° C., 7 ° C., 8 ° C., 9 ° C., and 10 ° C. was determined based on the equations (2) and (4). That is, the cooling water flow rate becomes Qh / 5, Qh / 6, Qh / 7, Qh / 8, Qh / 9, and Qh / 10 for each temperature difference.

  Then, a constant flow rate is circulated in the cooling water system at a temperature difference other than the peak for every temperature difference throughout the year by using the cooling water pump 4 having a capacity capable of delivering the cooling water flow rate. And for every said cooling water temperature difference, the annual power consumption was computed about the load factor of three patterns of the following patterns AC.

(C) Operation pattern In this case, the operation pattern of the heat source system is the annual load factor of the three patterns shown in FIGS. That is, in the pattern A, the daily load factor is 45% at midnight from 1 o'clock to 9 o'clock, 90% from 9 o'clock to 23 o'clock, and the monthly load factor is constant 95% throughout the year. The annual load factor is 65%.

  Pattern B has the same daily load factor as Pattern A, but the monthly load factor has a peak in July and August and gradually decreases in other months, with an annual load factor of 45%. It is.

  In the pattern C, the monthly load factor is the same as the pattern B, but the daily load factor is 0% from 1 o'clock to 9 o'clock, and the annual load factor is 30%.

(D) Trial calculation method throughout the year First, the exchange heat quantity of the month is determined based on each load (the daily load factor and the monthly load factor in FIG. 5) of the patterns A to C, and the outside air condition on the month and day Based on the above, the operating condition (cooling water temperature) of the cooling tower is calculated. Since the cooling water flow rate is constant, if the cooling water outlet temperature of the cooling tower is determined, the cooling water temperature condition is determined. For example, when a standard cooling tower is used (FIG. 4A), the cooling water temperature at the peak of summer (July, August, etc.) is set to 32 ° C., and the cooling water temperature of the turbo chiller 2 is set. When the difference is 5 ° C., for example, the cooling water flow rate at the peak is Qs / 5. Therefore, the cooling water flow rate including the peak time is operated throughout the year at a constant Qs / 5. When the load is small and the refrigerator performs partial load operation (for example, in Pattern B, March and April refer to the monthly load factor of 60%), the exchange heat amount also decreases, and the exchange heat amount on the cooling water side also decreases. Since the temperature difference is lower than 5 ° C., such an intermediate period load factor is also taken into consideration. Then, the total power consumption of the cooling water system when operated for one year under the conditions, that is, the annual power consumption of the cooling water pump 4 at the calculated cooling water flow rate (Qs / 5) is calculated, and the calculated temperature The power consumption of the turbo chiller 2 body under the conditions is calculated, the power consumption of the cooling fans 7a to 7c of the cooling tower 1 is calculated from the calculated temperature condition and the cooling water flow rate, and the total power consumption [kWh / Year].

Further, when the high-performance cooling tower is used (FIG. 4B), the annual power consumption is similarly obtained. That is, similarly, the heat exchange amount for the month is determined based on the loads of the patterns A to C (the daily load factor and the monthly load factor in FIG. 5), and the cooling tower is determined based on the outside air conditions on the month and day. The operating conditions (cooling water temperature) are calculated. For example, when a high-performance cooling tower is used (FIG. 4B), the cooling water temperature at the peak of summer (July, August, etc.) is set to 31 ° C., and the cooling water of the turbo refrigerator 2 is set. For example, when the temperature difference is 7 ° C., the cooling water flow rate at the peak is Qh / 7. Therefore, the cooling water flow rate including the peak time is operated throughout the year at a constant Qh / 7. When the load is small and the refrigerator performs partial load operation (for example, in Pattern C, January and February refer to the monthly load factor of 40%), the amount of heat exchange also decreases, so the amount of heat exchanged on the cooling water side also decreases. However, since the temperature difference is lower than 7 ° C., such an intermediate period load factor is also taken into consideration. Then, the total power consumption of the cooling water system when operated for one year under the conditions, that is, the annual power consumption of the cooling water pump 4 at the calculated cooling water flow rate (Qh / 7) is calculated, and the calculated temperature The power consumption of the turbo chiller 2 body under the conditions is calculated, the power consumption of the cooling fans 7a to 7c of the cooling tower 1 is calculated from the calculated temperature condition and the cooling water flow rate, and the total power consumption [kWh / Year].
That is, the cooling water inlet temperature of the refrigerator is calculated from the outdoor wet bulb temperature (statistical value) of the day and the performance curve of the cooling tower, and the input value of the turbo refrigerator is calculated from the partial load factor of the load pattern and the cooling water inlet temperature. By calculating [kw], cooling tower input value [kw], cooling water pump input value [kw], and calculating the daily power consumption, the power consumption is accumulated for the number of days per year, thereby increasing the annual power consumption. Find the amount.

(E) COP (coefficient of performance) of heat source system
The COP of the heat source system (excluding the chilled water pump) is obtained by the following equation (5).
Heat source system COP (coefficient of performance)
= Production heat of turbo chiller [kw] / Total power consumption of heat source system [kw]
・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ （5）

Here, the production heat quantity of the turbo refrigerator is calculated by the above formula (2). Further, the total power consumption of the heat source system (excluding the chilled water type chilled water pump) is calculated by the following equation (6).
Heat source system power consumption = (turbo refrigerator power + cooling tower fan power + cooling water pump power)
・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ （6）

(F) Trial calculation result (see Fig. 6)
FIG. 6 shows the annual power consumption with respect to the cooling water temperature difference for the standard cooling tower and the high performance cooling tower when the operations of the patterns A, B, and C are performed based on the above conditions. is there. According to this figure, it can be seen that the annual power consumption is lower at any temperature difference when the high-performance cooling tower is used than at the standard cooling tower. This is probably because the cooling water temperature of the high-performance cooling tower is about 1 ° C. lower than the cooling water temperature of the standard cooling tower throughout the year, which contributes to the efficiency of power consumption. Furthermore, it can be seen that the power consumption is the lowest when the cooling water temperature difference is around 7 ° C. in both the standard cooling tower and the high-performance cooling tower. That is, it can be seen that in both the standard cooling tower and the high performance cooling tower, the COP (coefficient of performance) of the heat source system shows the highest value when the temperature difference is around 7 ° C.

(C) Configuration for Realizing Maximum Value of COP From the above examination results, the inventors have made the following configuration in the heat source system shown in FIG. It came to the knowledge that COP of C could be made into the maximum value.

(A) When the turbo chiller 2 is operated 100% at the peak load in summer, the cooling water inlet temperature of the turbo chiller 2 is lowered by about 1 ° C. from the conventional 32 ° C. to about 31 ° C. in the cooling water system. Then, the cooling water inlet temperature is decreased by about 1 ° C. throughout the year.

  In order to realize this, it is necessary to improve the cooling capacity of the cooling tower 1, but for this purpose, the heat exchange area between the outside air and the cooling water is increased from 1.5 times to 2 times without increasing the power of the cooling fan. Use an enhanced high performance cooling tower.

(B) In order to further reduce the power consumption of the heat source system, the cooling water temperature difference ΔT at the inlet / outlet of the turbo chiller 2 is set to around 7 ° C. at the peak time (100% load). In order to realize this, the cooling water flow rate of the cooling water pump 4 is lowered from the standard type to reduce power consumption.

  Furthermore, the cooling water flow rate is determined based on the temperature difference of about 7 ° C. based on the production heat quantity of the centrifugal chiller 2 at the peak time (100% load), and is operated throughout the year at the cooling water flow rate (constant). I do.

  By operating under such conditions, the annual power consumption of the heat source system can be minimized and the COP can be maximized regardless of whether the standard type cooling tower or the high performance type cooling tower is used.

(D) Specific Device Configuration Hereinafter, a specific configuration of each device that satisfies the conditions (C), (a), and (b) in the heat source system of FIG. 1 will be described.
(A) About the cooling tower (high performance type cooling tower) 1

  The cooling tower 1 uses a cooling tower as shown in FIG. As described above, the design is such that the cooling water outlet temperature of the cooling tower 1 is 31 ° C. at the peak of summer (at 100% load). Specifically, for example, when the outside air temperature is 33.5 ° C. and the outside air wet bulb temperature is 27.5 ° C., the cooling tower 1 has a cooling water inlet temperature of 38 ° C. and a cooling water outlet temperature of 31 ° C. Do the design. Here, it is important to design the cooling fan 7a without increasing the power. As an example, a standard cooling tower (cooling water outlet temperature 32 ° C.) uses a cooling fan with a diameter of 2100 mm using a motor of 7.5 kW, and two such cooling towers are arranged side by side. Three cooling towers are arranged side by side using a cooling fan 7a having a diameter of 1800 mm using a 3.7 kW motor (cooling towers 1a to 1c). Further, by expanding the heat exchange area between the outside air and the cooling water per cooling tower (the area of the filler 19), the total heat exchange area between the outside air and the cooling water in the three refrigerators 1a to 1b can be calculated. The cooling capacity was improved by 1.5 to 2 times compared with the prior art, without increasing the cooling fan power, and a cooling water outlet temperature of around 31 ° C. was realized (FIG. 2B). Specifically, the increase in the heat exchange area was 1.5 to 2 times larger in the height direction while maintaining the width and depth of the filler 19 of the cooling tower 1. FIG. 8 shows the filler 19 (area enlarged portion 19 ') after area expansion. In addition, if comprised in this way, the efficiency of an installation area can be achieved. In FIG. 2A, reference numeral 20 denotes an outside air intake.

(B) Refrigerating machine 2 and cooling water pump 4 As the refrigerating machine 2, either a constant speed turbo refrigerating machine or an inverter-controlled turbo refrigerating machine can be used. In addition, since the refrigerator of such a performance is generally used conventionally, in order to implement | achieve this invention, the turbo refrigerator conventionally used can be used as it is.

  And as a design condition of the heat source system according to the present invention, the cooling water temperature difference based on the equations (2) and (4) is based on the amount of heat (a constant value) generated when the turbo refrigerator 2 is 100% loaded. The cooling water flow rate is determined to be around 7 ° C.

  For example, if the cooling water temperature difference of the conventional turbo refrigerator is 5 ° C., the cooling water flow rate can be set to about 5/7 as compared with the conventional heat source system. That is, the cooling water pump 4 having a capacity such that the cooling water flow rate at the peak time is about 5/7 of the conventional one is used. Thus, in order to make the inlet temperature difference around 7 ° C. with the cooling water while maintaining the heat generation amount of the conventional refrigerator, for example, the capacity of the cooling water pump 4 is about 5/7 of the capacity of the conventional type. A pump may be used.

(C) Others As described above, since the cooling water flow rate of the cooling water system can be set to a low flow rate, for example, about 5/7 of the conventional device, the cooling water system pipe 3 (outward pipe 3a, return pipe 3b) ) May be smaller than a conventional heat source system with a cooling water temperature difference of 5 ° C. Thereby, the manufacturing cost of the whole heat source system can also be reduced.

(E) Operation Description Since the heat source system of the present invention can be configured as described above, its operation will be described below. In the following description, the cooling tower 1a, 1b, 1c is a high performance type cooling tower (the peak cooling water temperature is around 31 ° C.), and the turbo refrigerator 2 is at the peak (at 100% load). ), The cooling water inlet temperature is around 31 ° C., the cooling water outlet temperature is around 38 ° C. (temperature difference ΔT = 7 ° C.), and the cooling water flow rate of the cooling water pump 4 is Qh / 7 (constant).
(A) Driving at peak

  At the peak time, the turbo chiller 2, the cooling towers 1a, 1b, 1c, and the cooling water pump 4 are all operated with a capacity of 100%. Accordingly, the outlet temperature of the cooling tower 1 is close to 31 ° C., and the cooling water at that temperature is sent out by the cooling water pump 4 toward the turbo refrigerator 2 through the outgoing pipe 3a.

  The cooling water flowing into the turbo refrigerator 2 enters the condenser 10 from the cooling water inlet 12a in the refrigerator 2 at a cooling water inlet temperature near 31 ° C., and 38 in the condenser 10 due to heat radiation from the refrigerant. The temperature rises to around 0 ° C., flows out from the cooling water outlet 12b, and flows into the cooling towers 1a to 1c from the inlet of the cooling tower 1a through the return pipe 3b. The cooling water that has flowed into the cooling towers 1a to 1c is cooled to around 31 ° C. by the cooling tower, and flows into the cooling water inlet 12a of the refrigerator 2 at the temperature. At this time, the bypass valve 18 is in a closed state, and the entire amount of the cooling water exiting the turbo refrigerator 2 flows into the cooling tower 1.

  Thus, at the peak time, the operation is performed with the cooling water inlet temperature around 31 ° C. and the cooling water temperature difference of the turbo chiller 2 fixed at around 7 ° C. At this time, as shown in FIG. 6, the COP (coefficient of performance) of the heat source system is the maximum value, and an efficient operation can be realized.

(B) Operation other than during peak time If the outside air wet bulb temperature becomes lower than the designed value of 27.5 ° C. due to fluctuations in the outside air conditions, the cooling water temperature becomes lower than 31 ° C. (see FIG. 7).

  If the operation of the turbo chiller 2 becomes a partial load (for example, 80%) due to a decrease in the outside air temperature or the like, the amount of heat exchanged by the turbo chiller 2 is also reduced to 80%. The amount of heat is also reduced. In this case, since the cooling water pump 4 continues to operate at a constant flow rate (Qh / 7), the cooling water temperature difference of the centrifugal chiller 2 is reduced by the amount of heat decreased from the above equations (2) and (4). It becomes smaller than 7 ° C. (for example, 5.6 ° C.).

  However, since the outside air temperature is lower than that at the peak time during such partial load, the cooling water temperature is also lower than the vicinity of 31 ° C. at the peak time (for example, 24 ° C.). Therefore, the cooling water inlet temperature of the turbo chiller 2 becomes 24 ° C., enters the condenser 10 from the cooling water inlet 12a, and rises to 29.6 ° C. due to heat radiation from the refrigerant in the condenser 10 (temperature difference). 5.6 ° C.) It flows out from the cooling water outlet 12b and flows into the cooling towers 1a to 1c from the inlet of the cooling tower 1a through the return pipe 3b. The cooling water that has flowed into the cooling towers 1 a to 1 c is cooled to 24 ° C. in the cooling tower, and flows into the cooling water inlet 12 a of the refrigerator 2 at the temperature.

  At such a partial load, the cooling water temperature decreases. However, as shown in FIG. 3, the COP of the turbo chiller 2 alone is improved when the cooling water temperature decreases from around 31 ° C. at the peak. . For example, in FIG. 3, when the cooling water temperature is 24 ° C., the COP is about 8.5 at a load factor of 80%, which is a great improvement over about 6.5 when the cooling water temperature is 31 ° C. and 100% load. Therefore, even if the cooling water temperature decreases, the COP of the heat source system does not decrease. Further, since the cooling water temperature (24 ° C.) is about 1 ° C. lower than that of the standard cooling tower (see FIG. 7), the turbo water is more turbocharged than the conventional turbo refrigerator even at the partial load. The COP of the refrigerator 2 (single unit) is improved. That is, since the cooling water temperature decreases by about 1 ° C. throughout the year, the COP of the turbo chiller 2 alone improves throughout the year, and as a result, the COP of the heat source system improves and is efficient throughout the year, including during partial loads. You can drive.

  Thus, even at the partial load, the cooling water pump 4 that selects the cooling water flow rate so that the temperature difference of the refrigerator 2 becomes 7 ° C. near the cooling water temperature of 31 ° C. at the peak time can be maintained at a constant flow rate throughout the year. By operating, the cooling water temperature difference can be made as large as possible, and the COP of the heat source system can be maximized throughout the year including the peak time.

  In the heat source system of the present invention described above, the refrigerator can be applied to either a constant speed turbo chiller or an inverter controlled turbo chiller.

  Since the heat source system of the present invention can be operated efficiently with a simple structure and can realize energy saving operation, it can be applied to various air conditioning facilities such as factories and office buildings. In particular, the present invention has the following effects.

  At the peak of summer, the cooling water temperature difference of the turbo chiller 2 is kept in the vicinity of 7 ° C., and an efficient operation with low power consumption can be performed.

  Further, since the cooling water flow rate is determined based on the cooling water temperature difference (near 7 ° C.) when the refrigerator 2 is operated at 100% load, the cooling water flow rate based on the standard cooling water temperature difference (5 ° C.). The cooling water flow rate can be smaller than that, and a low-capacity cooling water pump can be used.

  In addition, although the amount of heat generated by the turbo chiller 2 decreases at times other than the peak, the cooling water flow rate is maintained at a constant flow rate, so that the cooling water temperature decreases due to a decrease in the outside air wet bulb temperature. Therefore, the COP (coefficient of performance) of the refrigerator is improved, and an efficient operation with low power consumption can be performed even at a partial load.

  In the heat source system of the present invention, the refrigerator can be applied to an absorption refrigerator, an absorption chiller / heater, and the like.

  Therefore, it is possible to provide a heat source system that does not require complicated control such as rotational speed control by an inverter such as a cooling water pump, and that can realize efficient operation with a very simple configuration.

It is a block diagram showing the whole heat source system composition concerning the present invention. (A) is a figure which shows the detailed structure of the cooling tower in a system same as the above, (b) is a block diagram of the cooling tower in a system same as the above. It is a characteristic figure of COP with respect to the partial load factor of a general turbo refrigerator. (A) is a table | surface which shows each operating condition corresponding to the cooling water temperature difference in a standard type cooling tower, (b) is a table | surface which shows each operating condition corresponding to the cooling water temperature difference in a high performance type cooling tower. (A) is a table showing an operation pattern with an annual load factor of 65%, (b) is a table showing an operation pattern with an annual load factor of 45%, and (c) is a table showing an operation pattern with an annual load factor of 30%. It is a characteristic view which shows electric power consumption / year with respect to the cooling water temperature difference in a system same as the above. It is a table | surface which shows the annual cooling water temperature and cooling water flow rate in a system same as the above. It is a perspective view of the filler used for the cooling tower of a system same as the above.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cooling tower 1a-1c Cooling tower 7a-7c Cooling fan 2 Turbo refrigerator 3 Cooling water piping 4 Cooling water pump 6 Cooling water pump

Claims (1)

A cooling water system composed of a cooling tower, a refrigerator, a cooling water pump that circulates the cooling water by connecting between them with a pipe, and a cooling water system that supplies the cooling water cooled by the refrigerator to the load side with the cooling water pump In a heat source system consisting of
The cooling tower is set so that the cooling water outlet temperature of the cooling tower is lowered by about 1 ° C. throughout the year by expanding the heat exchange area between the outside air and the cooling water without increasing the fan power of the cooling tower. The cooling water outlet temperature at the time of 100% load operation of the cooling tower is configured to be close to 31 ° C,
Heat dissipation from cooling tower = (Production heat of turbo chiller + Power consumption of turbo chiller)
= (Cooling water temperature difference x Cooling water flow rate)
From the equation, the cooling tower and on the basis that uniquely determined production heat and power thereof in our Keru the refrigerator during the operation of the 100% load of the refrigerator, the refrigerator during the 100% load By setting the cooling water temperature difference between the cooling water inlet temperature and the cooling water outlet temperature in the vicinity of 7 ° C., which is higher than the conventional temperature difference of 5 ° C. , the flow rate of the cooling water is lower than the conventional one corresponding to the temperature difference of about 7 ° C. In addition to determining the flow rate ,
In the cooling water pump , the amount of production heat and power consumption of the refrigerator is lower than that of the 100% load, and the amount of production heat and power consumption of the refrigerator is lower than that of the 100% load and the temperature difference is Even at a partial load lower than 7 ° C., a constant flow of cooling water with the determined flow rate is circulated through the cooling water system throughout the year,
The cooling tower and the refrigerator are configured so that the COP (coefficient of performance) of the heat source system is always the maximum throughout the year during 100% load operation and partial load operation. Heat source system.

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