【作者】 刘福森；

【导师】 徐士鸣；

【作者基本信息】 大连理工大学 ， 制冷及低温工程， 2012， 硕士

【摘要】 目前,传统汽车制冷系统均采用消耗发动机动力的压缩制冷方式,造成能源的极大浪费,回收利用汽车尾气废热驱动吸收式制冷系统来代替传统压缩制冷方式,可以实现节能降耗的目的。由于单纯采用废热制冷不能满足汽车在任何行驶状态下对空调冷负荷的需求,根据废热驱动的吸收制冷循环特点以及对汽车制冷系统的技术要求,提出了一种以汽车发动机废热和动力联合驱动的新型吸收/压缩混合制冷循环。以金龙大客为实例,计算了客车空调冷负荷,为30kW。选用R124/DMAC为制冷工质对,在设计工况(空气温度35℃,冷凝温度55℃,制冷剂蒸发温度3℃,制冷负荷30kW)下,对混合制冷分别采用吸收制冷和压缩制冷两种极端情况进行了热力计算。得出了两子循环系统内各热质交换设备的设计负荷及进出口参数,作为系统设备设计或选型依据。本文对不同车速下汽车发动机的尾气排放参数进行了定量分析。给出了综合性能系数和发生器负荷率的定义,分析了两种溶液泵控制策略下,在不同的发生器负荷率和不同外界环境温度下,达到压缩机总耗功最小目标时,吸收／压缩混合制冷循环工作特性、循环内各设备的负荷特性及运行参数的变化规律。结果表明,设定工况下,当发生器负荷率为100%时,客车空调所需的冷负荷可以完全由吸收制冷子循环来提供,这时,混合制冷系统的综合性能系数达到最大,为14.85,由于这时的压缩机耗功为0,因此,混合制冷系统节省的发动机输出功率也是最大的,为7.89%的额定输出功率。当发生器负荷率降低时,吸收制冷子系统提供的制冷量不能够满足客车空调所需,不足的部分由压缩制冷子系统提供补充。另外,外界环境温度的变化会对吸收/压缩混合制冷循环产生较大的影响。计算结果表明,直接风冷条件下,高温环境采用废热制冷效果较差。在100%的发生器负荷率下,环境温度从35℃升高到40℃时,吸收制冷子循环的制冷量约降一半。当环境温度降低时,其情况与升高时相反,吸收制冷子循环制冷量会随环境温度降低而增加。更多还原

【Abstract】 At present, the traditional automotive cooling system uses the compression refrigeration that consumes engine power, causing a great waste of energy. Recycling vehicle exhaust waste heat to drive absorption chiller to replace traditional compression refrigeration way can achieve the purpose of energy saving. Since using the refrigeration system driven by waste heat simply cannot meet the cooling load needs of the car in any driving conditions, a novel absorption-compression hybrid refrigeration cycle (ACHRC) driven by waste heat and power from vehicle engines was proposed. It was based on the behaviors of the operation characteristics of the absorption refrigeration driven by the waste heat from automobile and the technical requirements for the vehicle cooling system.This paper taken Golden Dragon passenger as an example and calculate the cooling load of the bus air-conditioning. It is30kW. According to the air conditioning load for a bus, the thermal calculation of the ACHRC in which R124-DMAC is used as working fluid had been done under the given conditions. The given conditions are that the temperatures of cooling air, condensation and evaporation are35℃,55℃and3℃respectively and the bus air conditioning load is30kW. The loading characteristics and operation parameters of the absorption and compression refrigeration sub-systems which vary with the generator load ratio had been analyzed under two control strategies for the solution pump. The obtained results of two sub-cycles are used as the system equipment design or selection basis.This paper defined the coefficient of performance and generator load ratio and made a quantitative analysis on the parameters of engine exhaust emissions at different speed. Under two solution pump control strategies, when reaching the goal of the compressor minimum power consumption, it was analyzed that variation of the operating characteristics of the hybrid refrigeration cycle, the load characteristics of various devices and operating parameters under different generator load ratio or ambient temperatures.The results show that when the generator load ratio is100%, the cooling load of the bus air-conditioning could be solely provided by the absorption refrigeration sub-cycle at design conditions. At this time, the coefficient of performance of the hybrid refrigeration system reaches the maximum,14.85. When the compressor power consumption is0, the saved engine output power is also the largest. It is7.89%of rated output power. With the reduction of the generator load ratio, the cooling capacity of absorption refrigeration subsystem is not able to meet the bus air-conditioning required, and the insufficient part is provided by the compression refrigeration subsystem.In addition, the changes in ambient temperature will affect the absorption-compression hybrid refrigeration cycle. The results showed that under the direct air-cooled conditions, the effect of high ambient temperature is poor. At generator load ratio of100%, when the ambient temperature increased from35℃to40℃, the cooling capacity of absorption refrigeration sub-cycle is about to drop by half. When the ambient temperature is reduced, the cooling capacity of absorption refrigeration sub-cycle increases with the ambient temperature is reduced.更多还原