JP2006170569A - Absorption refrigerator and its operation control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform partial load operation of excellent thermal efficiency. <P>SOLUTION: A refrigerant pipe 14 extending from a low temperature regenerator 2 of a double effect absorption refrigerator to a condenser 3 is provided with a variable resistance valve V1. When the temperature difference ΔT (=T1-T2) between the (saturation) temperature T1 of refrigerant steam in an outlet side header H2 measured by a temperature sensor S1 provided at an upper part in the outlet side header H2 in the low temperature regenerator 2 during cooling operation, and the temperature T2 of a refrigerant (liquid) flowing in the refrigerant pipe 14 upstream of a refrigerant drain heat recovery apparatus 8, measured by a temperature sensor S2, is lower than a first predetermined value, e.g., 5°C, the opening of the variable resistance valve V1 is decreased by a controller C, and when the temperature difference ΔT is higher than a second predetermined value, e.g., 7°C, higher than the first predetermined value, the opening of the variable resistance valve V1 is increased. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an absorption refrigerator (including an absorption chiller / heater).

  When this type of equipment is used as an outdoor unit for an air conditioner that performs cooling or heating, it is installed with the ability to realize comfortable air conditioning even at the lowest and highest temperatures, so the majority of operation is part load It becomes the driving of the state.

And in order to improve the efficiency during the partial load operation, there is a technology that reduces the number of rotations of the cooling water pump and the cold / hot water pump during the partial load operation, thereby reducing the power cost of the incidental equipment and improving the efficiency. It is well known (for example, see Patent Documents 1 and 2).
JP 2000-161812 A JP 2000-274864 A

  In order to improve efficiency during partial load operation, not only reduce the power cost of incidental equipment, but also improve the thermal efficiency of each component in the absorption chiller itself taking into account the characteristics during partial load operation There was a need, and that was the challenge.

  High-temperature regenerator, low-temperature regenerator, condenser, evaporator, absorber, high-temperature heat exchanger, low-temperature heat exchanger, refrigerant pump, absorption liquid pump, etc. The absorption refrigerating machine is mainly characterized in that a variable resistor is provided between the low-temperature regenerator and the condenser of the refrigerant pipe extending from the low-temperature regenerator to the condenser.

  According to the present invention, the flow resistance of the refrigerant pipe from the high temperature regenerator to the condenser via the low temperature regenerator can be adjusted by the variable resistor. Therefore, the circulation amount of the refrigerant is reduced, the time for passing through the low temperature regenerator is shortened, and the time for releasing heat to the absorption liquid of the low temperature regenerator is insufficient. Since it is possible to extend the time and to extend the time for releasing heat to the absorption liquid of the low temperature regenerator, it is possible to improve the thermal efficiency during partial load operation.

  High-temperature regenerator, low-temperature regenerator, condenser, evaporator, absorber, high-temperature heat exchanger, low-temperature heat exchanger, refrigerant pump, absorption liquid pump, etc. Refrigerant drain heat recovery where a variable resistor is provided between the low temperature regenerator and condenser of the refrigerant pipe that reaches the condenser via the low temperature regenerator, and the refrigerant dissipates heat to the absorbing liquid upstream of the variable resistor A temperature difference T1-T2 between the saturation temperature T1 of the refrigerant in the low-temperature regenerator outlet header and the temperature T2 of the refrigerant flowing in the refrigerant pipe from the low-temperature regenerator to the condenser is smaller than a predetermined temperature Ta. Sometimes, the resistance of the variable resistor is increased, and when the temperature difference T1-T2 is greater than a predetermined temperature Tb (where Ta <Tb), the resistance of the variable resistor is decreased.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. The absorption refrigerator 100 of the present invention illustrated in FIG. 1 is a double-effect absorption chiller / heater using water as a refrigerant and a lithium bromide (LiBr) aqueous solution as an absorbent, and includes a gas burner 1B. High temperature regenerator 1, low temperature regenerator 2, condenser 3, evaporator 4, absorber 5, low temperature heat exchanger 6, high temperature heat exchanger 7, refrigerant drain heat recovery unit 8, refrigerant pump P1, absorption liquid pump P2, A variable resistance valve V1 and the like are provided, which are connected by absorption liquid pipes 9 to 12 and refrigerant pipes 13 to 18 as shown in the figure. Also, 20 is a brine pipe, 21 is a cooling water pipe, 22 is a pressure equalizing pipe, V2 to V4 are on-off valves, and C is a controller.

  In the absorption refrigerator 100 having the above-described configuration, when the on-off valves V2, V3, and V4 are closed, the cooling water is supplied to the cooling water pipe 21, the gas burner 1B is ignited, and the high-temperature regenerator 1 heats the absorption liquid. Evaporated and separated refrigerant vapor and an intermediate absorption liquid in which the concentration of the absorption liquid is increased by separating the refrigerant vapor are obtained.

  The high-temperature refrigerant vapor generated in the high-temperature regenerator 1 branches into the plurality of heat transfer tubes 2A from the refrigerant tube 13 via the inlet-side header H1 in the low-temperature regenerator 2, and is generated in the high-temperature regenerator 1. The intermediate absorption liquid that has entered the low temperature regenerator 2 via the high temperature heat exchanger 7 is heated by the absorption liquid pipe 10 through the tube wall of the heat transfer pipe 2A. Then, the refrigerant that has dissipated heat and condensed to the intermediate absorption liquid is discharged from the outlet header H <b> 2 to the refrigerant pipe 14, and enters the condenser 3 via the refrigerant drain heat recovery unit 8.

  The refrigerant heated by the low-temperature regenerator 2 and evaporated and separated from the intermediate absorption liquid enters the condenser 3, exchanges heat with water flowing in the cooling water pipe 21 to be condensed and liquefied, and is condensed and supplied from the refrigerant pipe 14. And enters the evaporator 4 through the refrigerant pipe 16.

  The refrigerant liquid that has entered the evaporator 4 and accumulated in the refrigerant liquid reservoir is sprayed onto the heat transfer pipe 20A by the refrigerant pump P1 interposed in the refrigerant pipe 17 and supplied with the brine (for example, water) via the brine pipe 20. The brine is evaporated by heat exchange, and the brine flowing inside the heat transfer tube 20A is cooled.

  Then, the refrigerant evaporated in the evaporator 4 enters the absorber 5 and is heated in the low-temperature regenerator 2 to evaporate and separate the refrigerant, so that the absorption liquid having a further increased concentration of the absorption liquid, that is, the low-temperature heat exchange by the absorption liquid pipe 11. It is supplied via the vessel 6 and absorbed by the concentrated absorbent dispersed from above.

  Absorbing liquid having a reduced concentration due to absorption of the refrigerant by the absorber 5, that is, the rare absorbing liquid, is branched into the absorbing liquid pipes 9A and 9B by the operation of the absorbing liquid pump P2 interposed in the upstream portion of the absorbing liquid pipe 9. A part flows through the low-temperature heat exchanger 6, the remaining part passes through the refrigerant drain heat recovery unit 8, and then merges and passes through the high-temperature heat exchanger 7 to the high-temperature regenerator 1 from the absorbing liquid pipe 9. Sent.

  When the absorption refrigeration machine 100 is operated as described above, the brine cooled by the heat of vaporization of the refrigerant in the heat transfer pipe 20A piped inside the evaporator 4 becomes a heat load (not shown) via the brine pipe 20. Since it can be circulated, cooling operation such as cooling can be performed.

  On the other hand, when the on-off valves V2, V3, and V4 are opened, and the rare absorbent is heated by the high temperature regenerator 1 by igniting the gas burner 1B without flowing the cooling water to the cooling water pipe 21, the high temperature regenerator 1 evaporates from the rare absorbent. The refrigerant mainly enters the absorber 5 and the evaporator 4 through the refrigerant pipes 13 and 15 having a low flow resistance, condenses by heat exchange through the brine supplied from the brine pipe 20 and the heat transfer pipe 20A, The brine flowing inside the heat transfer tube 20A is mainly heated by the heat of condensation at this time.

  The refrigerant condensed by the heating operation in the evaporator 4 enters the absorber 5 through the refrigerant pipes 17 and 18 and mixes with the absorbing liquid flowing in from the absorbing liquid pipe 12 by evaporating and separating the refrigerant in the high temperature regenerator 1. Then, it is returned to the high temperature regenerator 1 by the operation of the absorption liquid pump P2.

  The brine heated by the heat transfer tube 20A of the evaporator 4 is circulated and supplied to a heat load (not shown) through the brine tube 20, whereby a heating operation such as heating is performed.

  A controller C comprising a microcomputer, input means, etc. is provided with a temperature of the outlet side of the evaporator 4 for the brine to be circulated through the brine pipe 20 to a heat load (not shown). The refrigerant liquid collected by the refrigerant pump P1 and sprayed on the heat transfer tube 20A is cooled when flowing through the heat transfer tube 20A due to the evaporation heat, and discharged from the evaporator 4 to the temperature. The heating power of the gas burner 4 is controlled so that the brine outlet 4 temperature of the brine measured by the sensor S3 becomes a predetermined set temperature, for example, 7 ° C., and during the heating operation such as heating, from the high temperature regenerator 1 to the refrigerant pipe 13, 15 is mainly heated by the condensation heat of the high-temperature refrigerant vapor supplied via the temperature 15, and the temperature at the outlet side of the evaporator 4 of the brine discharged from the evaporator 4 and measured by the temperature sensor S3 is a predetermined value. It has a constant temperature, a well-known capacity control function prior to controlling the heating power of the gas burner 4 so for example, as 55 ° C..

  Furthermore, the controller C has a refrigerant vapor (in the outlet header H2) measured by the temperature sensor S1 provided in the upper part of the outlet header H2 installed in the low temperature regenerator 2 during cooling operation such as cooling. The temperature difference ΔT (= T1−T2) between the saturation T) temperature T1 and the temperature T2 of the refrigerant (liquid) flowing in the refrigerant pipe 14 upstream of the refrigerant drain heat recovery device 8 measured by the temperature sensor S2 is the first predetermined value. When the temperature difference ΔT is higher than the first predetermined value, for example, 7 ° C., the opening of the variable resistance valve V1 is decreased. A function to increase the degree is provided. Since the refrigerant is cooled and condensed by the surrounding absorption liquid when passing through the heat transfer tube 2A, the temperature measured by the temperature sensor S1 is the saturation temperature of the refrigerant.

  In the absorption refrigerator 100 of the present invention having the above-described configuration, the heat load for circulating the brine cooled to a predetermined 7 ° C. by the heat transfer pipe 20A in the evaporator 4 through the brine pipe 20 is small, and therefore the inside of the machine is reduced. During partial load operation in which the amount of circulating refrigerant decreases, the flow resistance decreases because the amount of refrigerant supplied from the high temperature regenerator 1 and flowing through the heat transfer pipe 2A in the low temperature regenerator 2 is small, and the refrigerant is transferred. It passes through the portion of the heat pipe 2A in a short time.

  However, when the refrigerant passes through the heat transfer tube 2A in a short time and heats the absorbing liquid through the tube wall to dissipate heat, in other words, the degree of cooling by the absorbing liquid decreases, the temperature sensor S2 measures. Since the temperature T2 of the refrigerant (liquid) that has been stopped does not decrease sufficiently and the value of the temperature difference ΔT becomes smaller than the first predetermined temperature 5 ° C., the controller C throttles the opening of the variable resistance valve V1.

  Therefore, the flow resistance of the refrigerant pipe 14 increases and the time for the refrigerant to pass through the heat transfer pipe 2A is extended, and the degree to which the refrigerant heats and absorbs heat through the tube wall of the heat transfer pipe 2A, that is, the absorption liquid Since the degree of cooling starts to increase and the refrigerant temperature T2 measured by the temperature sensor S2 decreases, the value of the temperature difference ΔT gradually increases and exceeds the first predetermined temperature of 5 ° C.

  That is, in the absorption refrigeration machine 100 of the present invention, the refrigerant sufficiently absorbs the absorption liquid when passing through the heat transfer tube 2A in the low temperature regenerator 2 even during partial load operation in which the amount of refrigerant circulating in the machine decreases. Since it can be heated, it is excellent in thermal efficiency even during partial load operation.

  Further, when the heat load increases during partial load operation, the amount of refrigerant circulating in the machine increases, and the amount of refrigerant flowing through the heat transfer pipe 2A in the low temperature regenerator 2 increases, the flow path resistance increases and the refrigerant is transmitted. Although the time for passing through the portion of the heat pipe 2A starts to increase, the degree to which the refrigerant heats and absorbs heat through the tube wall of the heat transfer pipe 2A, that is, the degree to which the refrigerant cools, increases the temperature sensor S2. The temperature T2 of the refrigerant being measured decreases.

  Therefore, the value of the temperature difference ΔT increases and exceeds the second predetermined temperature of 7 ° C. When such a state is reached, the opening of the variable resistance valve V1 is increased by the controller C and the refrigerant pipe is increased. 14 is reduced, the refrigerant easily passes through the heat transfer tube 2A, and the degree to which the refrigerant heats and absorbs heat through the tube wall of the heat transfer pipe 2A, that is, the degree to which the refrigerant cools. Decreases and the refrigerant temperature T2 measured by the temperature sensor S2 increases. Therefore, the value of the temperature difference ΔT gradually decreases and falls within the second predetermined temperature of 7 ° C. or less.

  That is, in the absorption refrigerator 100 of the present invention in which the variable resistance valve V1 whose opening degree can be controlled is provided in the refrigerant pipe 14 and the variable resistance valve V1 is controlled as described above, the amount of refrigerant circulating in the machine is reduced. Even when the partial load operation is performed, the heat efficiency is good, and the refrigerant pipe does not stay in the low temperature regenerator 2 even if the heat load increases during the partial load operation and the amount of refrigerant circulating in the apparatus increases. 14 smoothly flows into the condenser 8.

  For this reason, even if the heat load fluctuates, hunting of the refrigerant flow rate due to refrigerant stagnation does not occur. The temperature of the brine to be circulated does not fluctuate greatly.

  The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit described in the claims.

  For example, instead of the temperature sensor S1, the pressure sensor S4 is provided as shown by the phantom line in FIG. 2 so that the pressure of the refrigerant in the outlet header H2 can be measured, and the pressure is obtained from the refrigerant pressure measured by the pressure sensor S4. It is also possible to control the opening degree of the variable resistance valve V1 by the controller C as described above with the saturation temperature of the refrigerant as the saturation temperature T1.

  Further, the refrigerant drain heat recovery unit 14 is not necessarily provided. Further, an absorption refrigerator dedicated to a cooling operation such as cooling without installing the absorption liquid pipe 12 and the refrigerant pipe 15 may be used.

It is explanatory drawing which shows the structure of the absorption refrigerator of this invention. It is explanatory drawing which shows the principal part of the absorption refrigerator of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 High temperature regenerator 2 Low temperature regenerator 3 Condenser 4 Evaporator 5 Absorber 6 Low temperature heat exchanger 7 High temperature heat exchanger 8 Refrigerant drain heat recovery device 9-12 Absorption liquid pipe 13-18 Refrigerant pipe 20 Brine pipe 21 Cooling water pipe C Controller P1 Refrigerant pump P2 Absorption liquid pump V1 Variable resistance valve V2 to V4 On-off valve S1, S2, S3 Temperature sensor S4 Pressure sensor 100 Absorption refrigerator

Claims (4)

  High-temperature regenerator, low-temperature regenerator, condenser, evaporator, absorber, high-temperature heat exchanger, low-temperature heat exchanger, refrigerant pump, absorption liquid pump, etc. An absorption refrigerating machine, wherein a variable resistor is provided between a low temperature regenerator and a condenser of a refrigerant pipe extending from a low temperature regenerator to a condenser.   2. The absorption refrigerator according to claim 1, wherein a refrigerant drain heat recovery unit is provided upstream of the variable resistor to allow the refrigerant to dissipate heat to the absorption liquid.   The absorption refrigerator according to claim 1 or 2, wherein the temperature difference T1- between the saturation temperature T1 of the refrigerant in the low-temperature regenerator outlet header and the temperature T2 of the refrigerant flowing in the refrigerant pipe from the low-temperature regenerator to the condenser. An operation control method characterized by controlling the magnitude of the resistance of the variable resistor based on T2.   When the temperature difference T1-T2 is smaller than the predetermined temperature Ta, the resistance of the variable resistor is increased. When the temperature difference T1-T2 is larger than the predetermined temperature Tb (where Ta <Tb), the resistance of the variable resistor is decreased. The operation control method according to claim 3.

Images