集成喷射式热泵的大温差供热系统变工况研究

Study on Variable Condition of Large Temperature Differential Heating System With Integrated Ejector Heat Pump

在城市供热需求攀升的情况下,降低一次热网回水温度可提高供热能力且有利用回收低温余热资源。采用喷射式热泵可利用一次热网供水的高温热源降低回水温度,且有结构简单、运行稳定可靠的优点。本文构建了喷射式热泵系统模型,研究了集中供热质调节下喷射器热泵系统的变工况特性。结果表明:喷射式热泵可有效降低一次热网回水温度,在相同一次网供水温度下,一次网回水温度可降低22℃;随着一次网供水温度的升高,一次网回水温度、热泵系统COP和喷射器引射比逐渐升高但效率逐渐降低;在供热调节的过程中,随着室外温度的升高,一次网回水温度不断升高,效率逐渐降低;而当室外温度低于当地室外设计温度时,喷射器引射比和热泵系统COP急剧减小。

In the case of increasing urban heating demand, reducing the return water temperature of primary heating network can improve the heating capacity and utilize and recycle low-temperature waste heat resources. The ejector heat pump can use the high temperature heat source of the primary heat network to reduce the temperature of the return water, it has the advantages of simple structure, stable and reliable operation. In this paper, a model of ejector heat pump system is established to study the variable operating conditions of ejector heat pump system under central heating regulation. The results show that the ejector heat pump can effectively reduce the primary heat network return water temperature, and the primary network return water temperature can be reduced by 22 degree centigrade under the same primary network water supply temperature. With the increase of water supply temperature of primary network, the temperature of primary network return water, COP of the heat pump system and ejector ejection ratio increase gradually, the exergy efficiency decreases gradually. In the process of heating regulation, with the increases of outdoor temperature, the primary network return water temperature increases continuously, and the exergy efficiency decreases gradually;However, when the outdoor temperature is lower than the local design temperature, the ejector ejection ratio and the COP of the heat pump system decrease sharply.