基于内部损失分析方法对大温差吸收式热泵热力学特性的研究

In recent years, the CHP systems and industrial waste heat recovery systems based on absorption heat pumps have been proposed and applied in many real projects, which have realized considerable effect on energy saving and pollution exhaust reduction. The key components of this new technology are various kinds of absorption heat pumps with cooling and heating source of large temperature difference. As there is no unified method to direct the process design and the internal parameters optimization, the large temperature difference absorption heat pump faces a lot of difficulties on external performance evaluation, process structure design and optimal design of internal heat and mass transfer processes. This application aims to research the essence of the heat transformation of the absorption heat pump, using the new thermal parameter, "entransy", to set up the theoretical model of absorption heat pumps from the transformation between sensible heat entransy and concentration entransy. Based on the theoretical model, the evaluation method to evaluate the realization difficulty of the external parameters of absorption heat pumps with large temperature difference of external fluids can be obtained, and then the evaluation method can be used to direct the process structure construction. Then, based on the field synergy theory, the method to choose better heat and mass transfer structure and the internal parameters optimization can be obtained based on the entransy losses distribution of each unit inside absorption heat pumps. This application provides a new prospective for the absorption heat pump research, aims to set up an uniform design and optimization method based on internal losses analysis, for both the macroscopic view-the whole process structure and the element heat and mass transfer processes, to direct the development of the absorption heat pumps with large temperature difference of external fluids.

近年来，基于吸收式热泵的热电联产集中供热和工业余热利用技术被提出，并已在多个工程中被应用，实现了显著的节能减排效果。该技术的核心是各类热源/冷源侧大温差要求的吸收式热泵。由于目前吸收式热泵的流程构建和内部参数优化等在理论上还没有统一的指导方法，使得大温差吸收式热泵的外部热参数性能评价、流程构建及内部传热传质过程优化等都面临很大困难。本申请试图从吸收式热泵实现热量变换的本质出发，利用新的热学参数火积，从显热火积与浓度火积相互转换的角度，提出吸收式热泵的理论模型；基于此理论模型，得到大温差吸收式热泵外部热参数实现难度的评价方法，并由此指导流程结构的构建；进而利用场协同的思想，提出以内部各环节火积耗散分布为基础的传热传质结构选择和内部参数优化设计方法。本申请从新的视角看问题，试图建立起一套统一的从宏观的流程结构到微元的传热传质过程基于内部损失进行优化设计的方法，从而指导大温差吸收式热泵的发展。

近年来，基于吸收式热泵的热电联产集中供热和工业余热利用技术被提出，并已在多个工程中被应用，实现了显著的节能减排效果。该技术的核心是各类冷源/热源侧大温升/降要求的吸收式热泵。由于理论上对于吸收式热泵的研究还没有统一的指导方法，使得吸收式热泵的外部热参数性能评价、流程结构分析及内部传热传质过程优化都面临很大困难。为此，本项目试图从吸收式热泵实现热量品位变换的本质出发，基于吸收式热泵内部真实发生的物理过程提出了吸收式热泵的全新的理论模型，提出了温度提升系数，利用温度提升系数和COP两个相对独立的参数来全面得描述吸收式热泵的性能。由此给出了溶液层次的热力学模型，建立了吸收式热泵内部热量转换的基本框架，通过各传热传质过程建立了内部框架与外部源之间的关系，指出吸收式热泵优化设计的方向：应尽量减小各传热传质过程的耗散，实现尽可能高的外部源侧的温度提升。基于此理论模型，得到吸收式热泵外部热参数实现难度的评价方法。进而，进一步发展了吸收式换热器的新概念，提出了第二类吸收式换热器，提出了利用两类吸收式换热器实现热量长距离输送的系统，为低品位工业余热长距离输送用于建筑供热提出一种可行的途径。提出全新的立式吸收式换热器流程，减少内部的不匹配换热损失，提高吸收式换热器的性能。提出用温度效率来表征吸收式换热器的基本性能。进一步，从流程研究深入到内部传热传质过程研究，在实验研究几类典型的传热传质过程性能的基础上，对典型的三股流吸收过程的匹配特性开展研究，通过火积耗散定义热阻提出了微元传热传质过程的匹配特性，指导实际吸收器的具体设计。通过本项目，从外部性能到内部传热传质过程，从整体的流程结构到微元的传热传质方式，从溶液层次的热量变换到热量传递与热量变换均存在的实际过程，初步给出了一整套热力学分析方法。在本项目指导下，典型的立式吸收式换热器被研发出来，并成功用于多个实际工程，支撑了未来一种全新的分散供热模式，有着显著的社会效益和应用价值。