Heat Source Apparatus , Heat Source System, And Method Of Controlling Heat Source Apparatus

Abstract

A turbo chiller that can run continuously even with a low load, for example, less than 10% load, is provided. In a turbo chiller having a low-load mode for repeatedly controlling stopping and starting of the turbo chiller when a coolant inlet temperature measured by a coolant inlet temperature sensor is equal to or lower than a first temperature forming a temperature difference with respect to the coolant outlet temperature, a stop limit mode for stopping the turbo chiller when the coolant inlet temperature or the coolant outlet temperature is equal to or lower than a second temperature below the first temperature is provided.

1 . A heat source apparatus comprising:
 a compressor for compressing a refrigeration medium;   a condenser for condensing the refrigeration medium compressed by the compressor;   an expansion valve for expanding the refrigeration medium condensed by the condenser;   an evaporator for evaporating the refrigeration medium expanded by the expansion valve;   a coolant supply pipe for supplying coolant heat exchanged with the evaporator to an external load;   a coolant outlet temperature measuring part for measuring a coolant outlet temperature of the coolant flowing through the coolant supply pipe;   a coolant return pipe for performing heat exchange with the external load and for returning the coolant to the evaporator;   a coolant inlet temperature measuring part for measuring a coolant inlet temperature of the coolant flowing through the coolant return pipe; and   a control unit for performing control so that the coolant outlet temperature is a preset coolant outlet temperature,   wherein the control unit has a low-load mode in which the heat source apparatus is controlled to repeatedly switch between stopping and starting when the coolant inlet temperature measured by the coolant inlet temperature measuring part is equal to or lower than a first temperature forming a prescribed temperature difference with respect to the preset coolant outlet temperature, and   wherein the control unit has a stop limit mode in which the heat source apparatus is stopped when the coolant inlet temperature or the coolant outlet temperature is equal to or lower than a second temperature below the first temperature.   
   
   
       2 . A heat source apparatus according to  claim 1 , wherein the second temperature is lower than the preset coolant outlet temperature. 
   
   
       3 . A heat source apparatus according to  claim 1 , wherein the second temperature is equal to or higher than a minimum temperature which the external load permits. 
   
   
       4 . A heat source apparatus according to  claim 1 , wherein the control unit can selectively switch between the low-load mode and the stop limit mode. 
   
   
       5 . A heat source apparatus according to  claim 4 , wherein the control unit can selectively switch between each of the modes during operation of the heat source apparatus, and when switching from the stop limit mode to the low-load mode, the low-load mode is executed after a prescribed period of time has elapsed. 
   
   
       6 . A heat source apparatus according to  claim 4 , further comprising:
 a coolant supplying part for supplying coolant for absorbing heat of condensation from the refrigeration medium flowing through the condenser,   wherein, when the temperature of the coolant flowing into the condenser is at a prescribed value or lower, the control unit can select the stop limit mode.   
   
   
       7 . A heat source apparatus according to  claim 1 , wherein the coolant outlet temperature measuring part and/or the coolant inlet temperature measuring part comprise a plurality of temperature sensors provided at different positions in a circumferential direction at an identical radial position in an identical cross section of the coolant supply pipe and/or the coolant return pipe, and
 the control unit uses an average value of the output values from each temperature sensor.   
   
   
       8 . A heat source system comprising a plurality of the heat source apparatuses according to  claim 1 . 
   
   
       9 . A control method for a heat source apparatus which includes
 a compressor for compressing a refrigeration medium,   a condenser for condensing the refrigeration medium compressed by the compressor,   an expansion valve for expanding the refrigeration medium condensed by the condenser,   an evaporator for evaporating the refrigeration medium expanded by the expansion valve,   a coolant supply pipe for supplying coolant heat exchanged with the evaporator to an external load,   a coolant outlet temperature measuring part for measuring a coolant outlet temperature of the coolant flowing through the coolant supply pipe,   a coolant return pipe for performing heat exchange with the external load and for returning the coolant to the evaporator, and   a coolant inlet temperature measuring part for measuring a coolant inlet temperature of the coolant flowing through the coolant return pipe;   which performs control so that the coolant outlet temperature is a preset coolant outlet temperature; and   which executes a low-load mode in which stopping and starting of the heat source apparatus is repeatedly controlled when the coolant inlet temperature measured by the coolant inlet temperature measuring part is equal to or lower than a first temperature forming a prescribed temperature difference with respect to the preset coolant outlet temperature,   the control method for the heat source apparatus comprising:   executing a stop limit mode for stopping the heat source apparatus when the coolant inlet temperature or the coolant outlet temperature is equal to or lower than a second temperature below the first temperature.