Авіаційно-космічна техніка та технологія (Dec 2018)
IMPROVING THE EFFICIENCY OF THE GAS ENGINE HEAT’S UTILIZATION BY STAGE TRANSFORMATION
Abstract
It was carried out the analysis of the heat utilization efficiency of the cogeneration module of the gas reciprocating engine with the cold produced by an absorption Li-Br chiller in an autonomous electric, heat and cold supply unit. It was revealed the presence of 30% heat losses of the total heat removed from the cogeneration gas reciprocating module and is due to the inconsistency of the joint operation modes of the absorption Li-Br chiller and the gas reciprocating engine. This inconsistency is caused by the contradictory conditions of their effective operation according to the temperature of the return coolant at the outlet of the absorption Li-Br chiller and at the entrance to the engine cooling system. The thermal state of the gas reciprocating engine is ensured by maintaining the temperature of the return (cooled) coolant not more than 70 °C at the inlet. At the same time, during the transformation of the coolant heat into the cold in an absorption Li-Br chiller, the temperature reducing in the machine is no more than 10 ... 15 °С, i.e. up to 75 ... 80 °С, if the temperature of the heat coolant at the outlet of the cogeneration gas reciprocating module (at the inlet of the absorption Li-Br chiller) is 90 °С. Due to the conflicting requirements for efficient operation of the gas reciprocating engine and absorption Li-Br chiller for the coolant temperature to maintain the temperature of the return coolant at the engine inlet at a safe level of 70 °C, it is additionally cooled in the "emergency heat release" cooling tower. It was studied the stage transformation of heat into cold applying ejector and absorption Li-Br chiller, and the evaporator section of the ejector chiller’s generator was on the coolant line before the absorption Li-Br chiller and the economizer section of the generator was on the coolant line after it. It was determined the dependence of the units’ cooling capacity increase on the thermal coefficient of the ejector chiller and the possibility of the unit’s cooling capacity increase by 10 ... 15% applying stage transformation of heat
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