JP5284850B2 - Method and apparatus for switching control of number of absorption chiller / heater - Google Patents

Description

  The present invention relates to a number switching control method and apparatus capable of selecting / switching the operating number of a plurality of absorption chiller / heaters to an appropriate number.

Conventionally, in the control of the number of a plurality of absorption chiller / heaters, it is necessary to operate with an appropriate number according to the fluctuation of the air conditioning load. The method of estimating the air conditioning load from the temperature difference of cold / hot water is generally used, but when the flow of cold / hot water is changed (inverter control of a water pump, bypass, etc.), the load cannot be correctly captured.
Assuming that the air conditioning load is the amount of exchange heat, the flow rate is multiplied by the difference between the temperature of the cold / hot water sent from the absorption chiller / heater and the temperature of the incoming cold / hot water. Generally, since the cold / hot water inlet / outlet temperature of each absorption chiller / heater is measured, if a predetermined flow rate is supplied, it is possible to calculate the air conditioning load based on this temperature difference.

  When the flow rate of cold / hot water changes, such as when the water pump is controlled by an inverter or when cold / hot water is bypassed from the inlet to the outlet of the absorption chiller / heater, the temperature difference alone is not sufficient to calculate the air conditioning load. Without a flow rate. When the inverter command of the water pump is known, or when the necessary cold / hot water flow rate is measured by a flow rate sensor or the like, it is possible to obtain flow rate information from these information.

  2. Description of the Related Art Conventionally, there is known an air conditioning heat source number control device that measures a cold / hot water flow rate and a bypass flow rate thereof using a flow meter in order to estimate a load (see, for example, Patent Document 1). Also, an absorption chiller control device provided with a device for measuring the load factor of the direct load side phi coil unit is known (see, for example, Patent Document 2). However, if the water pump is different from the control device for the absorption chiller / heater and the inverter command value is unknown, or if it is not possible to install a device that measures the flow rate sensor and load factor due to cost and installation environment problems The air conditioning load cannot be calculated. For this reason, the cold / hot water flow volume required in order to calculate an air-conditioning load correctly may become unknown.

Japanese Patent Laid-Open No. 2000-257938 (second page, FIG. 1) JP-A-7-71836 (2nd page, FIG. 1)

  The problem to be solved is that an expensive flow rate sensor for measuring the flow rate of cold / hot water must be added in order to improve the accuracy of air conditioning load calculation.

  The most important aspect of the present invention is to estimate the required chilled / hot water flow rate and improve the load estimation calculation accuracy from the relationship between the amount of combustion and the chilled / hot water temperature in the absorption chiller / heater without adding a sensor for flow rate measurement. Features.

Estimate the flow of cold / hot water flowing through each absorption chiller / hot water machine from the combustion amount and temperature difference, and the flow of chilled / hot water bypassing the absorption chiller / hot water machine, without adding a flow sensor for flow measurement, the accuracy of air conditioning load calculation A method for improving the above will be described.
(1) Estimate the flow rate of water flowing through each absorption chiller / heater by Equation 1.

Here, G is the actual cold / hot water flow rate, G rating is the rated cold / hot water flow rate, ΔT is the temperature difference (measurement), and ΔT _est is the expected temperature difference when the rated flow rate is assumed. From the energy balance, the flow rate for actually passing the absorption chiller / heater can be calculated from Equation (1). ΔT is known because it is the temperature difference between the inlet and outlet of the chiller / heater. Since the G rating is design data, it is also known. ΔT _est is proportional to the amount of combustion, and assuming that the temperature difference of specification at a combustion rate of 100% is ΔT ₁₀₀ , Equation 2 is derived. However, since the absorption chiller / heater has a delay with respect to the combustion amount, a first-order lag characteristic is introduced with respect to the combustion amount input. Note that this delay may be expressed by a dead time or a higher-order delay.

  Here, MVFuel is the combustion amount ratio. If the combustion ratio is known, Equation 3 is obtained from Equation 1 and Equation 2.

  From this equation 3, G can be calculated. In Equation 2, the relationship between the combustion ratio and the predicted temperature difference is expressed in a linear form, but this relationship can also be expressed by a nonlinear function (polynomial, table function, etc.).

(2) Next, the bypass flow rate is estimated. Suppose that a part of the chilled / hot water upstream of the absorption chiller / heater is bypassed to the downstream without passing through the absorption chiller / heater, and considering the energy balance at the downstream junction, Equation 4 is established. To do.

Here, G _b is the bypass flow, the To _k is the outlet temperature of the absorption chiller heater, Tit the average value of the absorption chiller heater inlet temperature, Tot is the outlet collection unit temperature. To _k and Tit are _obtained from the cold / hot water inlet / outlet temperature of each absorption cold / hot water machine. For Tot, a temperature sensor is provided and measured. When G _b <0, it is considered that G _b = 0.

(3) Next, the air conditioning load is calculated. When the rated air-conditioning load is 100%, the air-conditioning load factor considering the change in the chilled water flow rate is defined as the following formula 5.

Here, Ltot the load factor, Tit the average value of the absorption chiller heater inlet temperature, SP is absorbed chiller outlet collection header temperature setpoint, Tit rating absorption chiller inlet set header temperature rated value, Tot ratings absorption chiller heater outlet collection header temperature rated value, G _k is the flow rate of water flow to the absorption chiller heater, the flow rate G _k ratings for passing water absorption chiller heater (rated), G _b is the bypass flow rate is there.

(4) Next, the number is determined. By determining the number of units to be activated based on the load factor shown in (3), it is possible to capture the load according to the change even when the cold / hot water flow rate changes. By determining the number of units based on this load factor, it is possible to select an appropriate number with respect to a change in the flow rate of cold and hot water without adding a flow rate sensor.

The number switching control method of the absorption chiller / heater of the present invention is a method for controlling the switchover of the number of a plurality of absorption chiller / heaters, wherein the amount of combustion, the chilled / hot water inlet temperature and the chilled / hot water outlet temperature in each absorption chiller / hot water Based on the difference in temperature, the chilled / hot water flow rate for passing each absorption chiller / hot water machine and the chilled / hot water flow rate for bypassing the absorption chiller / hot water machine are estimated, the air conditioning load factor is calculated, and startup is based on this load factor The number of units to be selected is selected.

  Moreover, the number switching control device of the absorption chiller / heater of the present invention is a device that controls the switching of the number of a plurality of absorption chiller / heaters, and an individual control device that controls each absorption chiller / heater, and an individual control device The unit control device outputs a start / stop command to the vehicle, and the unit control device determines the number of operating units that meet the load condition from the cold / hot water inlet / outlet temperature and the combustion ratio transmitted from each individual control unit. The start / stop command is transmitted to each individual control device, and the individual control device determines the amount of fuel input so that the cold / hot water outlet temperature of each absorption chiller / heater becomes a preset temperature. In addition, according to a start / stop command from the number control device, fuel is supplied to / cut off from the absorption chiller / hot water machine.

Since this invention is comprised as mentioned above, there exist the following effects.
(1) In the absorption chiller / hot water machine, even if the chilled / hot water flow rate changes, the load can be captured according to the change. By determining the number of starting units based on this load factor, Without being provided, it is possible to determine an appropriate number of startups for changes in the flow rate of cold and hot water.

It is a flow sheet which shows the air-conditioning system in the device of the present invention. It is a block diagram which shows an example of the control apparatus in the apparatus of this invention. It is a block diagram which shows an example of the cold water flow volume estimation calculation block in the apparatus of this invention. It is a block diagram which shows an example of the calculation block of the load factor in the apparatus of this invention. It is a diagram which shows an example of the number change rule for implementing the method of this invention. It is a graph which shows the relationship between the time in Comparative Example 1, and an air-conditioning load. It is a graph which shows the relationship between the time in the comparative example 1, an assembly header inlet temperature, and an assembly header exit temperature. It is a graph which shows the relationship between the time in Comparative Example 1, and a cold water flow volume. It is a graph which shows the relationship between the time in Comparative Example 1, a load factor, and the number of operation. It is a graph which shows the relationship between the time in Example 1, and an air-conditioning load. It is a graph which shows the relationship between the time in Example 1, an aggregate header inlet temperature, and an aggregate header exit temperature. It is a graph which shows the relationship between the time in Example 1, and a cold water flow volume. It is a graph which shows the relationship between the time in Example 1, a load factor, and the number of operation.

  The purpose of selecting and switching the number of operating absorption chiller / heater units to an appropriate number is to set the required chilled / hot water flow rate without providing a sensor for flow rate measurement from the relationship between the combustion amount and the chilled / hot water temperature. Realized by estimation.

  Embodiments of the present invention will be described below, but the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications. FIG. 1 is a flow sheet showing an air conditioning system.

  That is, FIG. 1 shows an air conditioning system including three absorption chiller / heaters as an example. It consists of three units of chilled water heaters 1, 2, and 3, and the number of operating units is determined according to the load. Further, the flow rate of the cold water flowing through the system is determined by the number of rotations of the primary cold water pumps 4, 5, 6 and the secondary cold water pumps 7, 8, 9 and the opening of the circulation valves 10, 11. 12 and 13 are air conditioning loads. Reference numerals 14, 15, and 16 denote cooling water pumps, 17 denotes a cold water inlet header, 18 denotes a cold water outlet header, 20 denotes a cold water outlet secondary header, 21, 22, and 23 denote cooling water flow control valves, and 24 denotes a cold water bypass pipe.

  FIG. 2 shows a configuration example of the control device, and outputs individual control devices 31, 32, 33 for controlling the respective absorption chiller heaters 1, 2, 3 and start / stop commands to the individual control devices. The number control device 35 is configured. The number control device 35 determines the number of operating units that meet the load condition from information (cold water inlet / outlet temperature, combustion ratio, etc.) transmitted from each individual control device, and transmits start / stop commands to each individual control device. . In the individual control device, the amount of fuel input is determined so that the cold / hot water outlet temperature of each absorption chiller / heater becomes a preset temperature, but the absorption chilled / hot water is determined according to the start / stop command from the unit control device. Implement fuel injection / shut-off to the aircraft.

  More specifically, the apparatus according to the present embodiment is used to output individual start / stop commands to the individual control devices 31, 32, 33 that control the respective absorption chiller / heater 1, 2, 3, and the individual control device. The number control device 35 is configured to determine the number of operating units that meet the load condition from the cold / hot water inlet / outlet temperature and the combustion ratio transmitted from each individual control device, and start / A stop command is transmitted, and in the individual control device, the fuel input amount is determined so that the cold / hot water outlet temperature of each absorption chiller / heater becomes a preset temperature, and the start / stop command from the unit control device 35 is determined. In response to this, the fuel is supplied to or cut off from the absorption chiller / heater.

  In the apparatus configured as described above, the cold / hot water that causes each absorption cold / hot water machine to flow from the combustion amount in each absorption cold / hot water machine 1, 2, 3 and the temperature difference between the cold / hot water inlet temperature and the cold / hot water outlet liquidity. The flow rate and the cold / hot water flow rate for bypassing the absorption chiller / heater by the bypass pipe 24 are estimated, the air conditioning load factor is calculated, and the number of units to be activated is selected based on this load factor.

  In the number control device 35 in FIG. 2, the number of units to be operated is determined using the methods shown in the above (1) to (4). FIG. 3 shows an example of the cold water flow rate estimation block. In the cold / hot water flow rate block, the cold / hot water flow rate ratio (the ratio between the rated flow rate and the actual flow rate) is determined from Equation 3, and the cold / hot water flow rate flowing through each absorption chiller / heater is calculated. From the flow rate flowing through each absorption chiller / heater, the outlet temperature, and the chilled / hot water inlet header temperature, the bypass flow rate is calculated from Equation 4.

  After calculating the cold / hot water flow rate and bypass flow rate flowing through each absorption chiller / hot water machine, the load factor is calculated from Equation (5). FIG. 4 shows an example of a load factor calculation block. Based on the calculated load factor, the number of operating units for each load factor is determined, and based on this, start / stop commands are output to each absorption chiller / heater. As shown in FIG. 5, the rule for switching the number of units is to operate two units when the load exceeds a set value L1, and to three units when the load exceeds L2, and to reduce the number, one unit is less than L1 ′, L2 'or less and 2 units.

The effect of the present invention is shown by simulation. The present invention is effective in selecting the number of units when the cold water flow rate is changed at a partial load. As a premise, it is assumed that no flow sensor capable of measuring the cold water flow rate is provided. Comparison Example 1 and Example 1 under the following conditions are compared and the effect is described.
Comparative Example 1: The number of units is determined using the load calculated from the header outlet / inlet temperature difference. Load factor = measured temperature difference / rated temperature difference × 100
Example 1: The number is determined by the method of the present invention. As external input conditions, at 30 minutes, the load is changed from 100 to 50%, and the cold water flow rate is changed from 100 to 60%. In both Comparative Example 1 and Example 1, the number of units is changed from 3 to 2 when the load factor falls below 55%.

FIG. 6 shows the relationship between time and air conditioning load in Comparative Example 1, FIG. 7 shows the relationship between time in Comparative Example 1 and the aggregate header inlet temperature and aggregate header outlet temperature, and FIG. 9 shows the relationship with the cold water flow rate, and FIG. 9 shows the relationship between the time, the load factor, and the number of operating units in Comparative Example 1.
10 shows the relationship between the time and the air conditioning load in the first embodiment, FIG. 11 shows the relationship between the time in the first embodiment, the aggregate header inlet temperature, and the aggregate header outlet temperature, and FIG. FIG. 13 shows the relationship between time, the load factor, and the number of operating units in Example 1.

  From the simulation results in Comparative Example 1 and Example 1, it was found that the three-unit operation was continued in Comparative Example 1, and the two-unit operation was switched in Example 1. Since the load is 50%, it is a condition that allows two units to be operated. In addition, in the case of three-unit operation, since one unit becomes a low-load operation compared with two-unit operation, the efficiency is poor. For this reason, it is preferable to operate two units. From the above, by applying the present invention, an appropriate number of units can be selected.

  In the absorption chiller / heater, it is possible to estimate the required chilled / hot water flow rate without providing a sensor for measuring the flow rate from the relationship between the combustion amount and the chilled / hot water temperature, and to improve the load estimation calculation accuracy.

1, 2, 3 Chilled / hot water machine 4, 5, 6 Primary chilled water pump 7, 8, 9 Secondary chilled water pump 10, 11 Circulating valve 12, 13 Air conditioning load 14, 15, 16 Cooling water pump 17 Chilled water inlet header 18 Chilled water outlet Header 20 Chilled water outlet secondary header 21, 22, 23 Cooling water flow rate control valve 24 Chilled water bypass piping 31, 32, 33 Individual control device 35 Number control device

Claims (2)

A method of controlling the number switching of a plurality of absorption chiller heater, combustion quantity in each absorption chiller, the temperature difference between the hot and cold water inlet temperature and cold water Atsushi Ideguchi, the actual and rated hot and cold water flow By determining the ratio to the chilled / hot water flow rate, the chilled / hot water flow rate for passing each absorption chiller / hot water machine is estimated by calculation, and then the flow through each absorption chiller / hot water machine, the outlet temperature, and the chilled / hot water inlet header temperature are estimated. the cold water flow to bypass absorption chiller heater estimated by calculation, these flow rates, the rated value of the flow rate that passed through the absorption chiller heater, the average value of each absorption chiller heater inlet temperature, the absorption chiller outlet Calculate the air conditioning load factor from the aggregate header temperature setting value, the absorption chiller / heater inlet collective header temperature rating value and the absorption chiller / heater outlet collective header temperature rating value, and select the number of units to start based on this load factor Absorption chiller / heater stand Switching control method. An apparatus for controlling the switching of the number of absorption chiller / heater units, and an individual controller for controlling each absorption chiller / heater, and a unit controller for outputting start / stop commands to the individual controller In the unit control device , each absorption chiller water heater is determined by determining the ratio between the rated chilled water flow rate and the actual chilled water flow rate from the chilled water inlet / outlet temperature and the combustion ratio transmitted from each individual control device. Estimate the flow rate of chilled / hot water to flow through, and estimate the flow rate of chilled / hot water that bypasses the absorption chiller / heater from the flow rate that flows through each absorption chiller / heater, the outlet temperature, and the cold / hot water inlet header temperature. Flow rate, the rated value of the flow rate of water flowing through the absorption chiller / heater, the average value of the absorption chiller / heater inlet temperature, the set value of the absorption chiller / heater outlet set header temperature, the absorption chiller / heater inlet set header temperature rating and absorption Cold and hot water From the outlet collection header temperature rated value, calculates the air-conditioning load factor, determines the number of operating that matches this load condition, so as to transmit a start / stop command to each of the individual control device, the absorption cold in individual control device The amount of fuel input is determined so that the cold / hot water outlet temperature of the water machine becomes a preset temperature, and the fuel is supplied to / cut off from the absorption cold / hot water machine according to the start / stop command from the number control device. The number change control device of the absorption chiller / heater characterized by having done so.

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