热湿循环的基础研究

Heat and humidity handling process is the basic process in the area of built environment and waste heat utilization. The existing researches proposed many specific optimization methods for the actual heat-humidity systems in the perspectives of system parameters, processes and exergy analysis. However, compared with the heat-work conversion cycle, there lacks a general theory about heat-humidity cycle, which can be shown in the following aspects: a lack of ideal heat-humidity cycle; a lack of intuitive diagrams, like P-V diagram or T-S diagram, to deal with heat-humidity cycle; the optimization orientation and limit of the actual heat-humidity cycle needs to be further studied and a universal guiding principle is needed. By analyzing all kinds of heat and moisture transfer processes, this project will explore and establish an ideal heat-humidity cycle working in two moisture sources and obtain its efficiency expression, which can play a guiding role in heat and humidity handling process. With reasonable state parameter group being the axes, the state diagrams can be gained and the processes, moisture transfer quantity and energy consumption can thus be reflected on the diagrams. Besides, an engineering application oriented experimental system covering a wide range of conditions will be set up under the guidance of the ideal cycle. The performance of the experimental system will be tested, especially under the high temperature and high humidity condition. Consequently, optimization criteria for all sorts of actual heat-humidity cycles will be proposed.

热湿处理过程是建筑环境及余热利用等领域的基本过程。现有研究针对各种实际热湿循环从系统参数、流程及火用分析等角度给出了具体优化方法。但相较于热功转换循环，热湿循环的理论体系尚待完善，主要表现为：没有可逆条件下的理想循环概念；缺少类似于p-v图、T-s图的直观分析方法；实际热湿循环的优化方向和限度有待进一步研究并形成统一的普适性指导原则。本项目拟通过分析各类热湿处理系统，提出两湿源间的理想热湿循环并给出其效率表达式；合理选取表征工质状态变化的参数，建立热湿循环的状态图分析法，将热湿循环流程、传湿量和循环能耗等反映在状态图中；以理想热湿循环为指导，搭建并优化以实际工程应用为导向的热湿循环实验系统，测试其不同工况的性能，尤其是高温高湿工况的性能与热湿传递特性，最终提出可应用于各类实际热湿处理系统的优化准则。

热湿处理过程是建筑环境控制及余热利用等领域的基本过程，现有研究针对各种实际热湿循环，从系统参数、流程及火用分析等角度给出了具体优化方法，但相较于卡诺循环理论指导下的热功转换循环，热湿循环的理论体系尚待完善。本课题建立了可逆的理想热湿处理循环，并针对溶液热湿循环给出了基于焓湿图的等效T-Q图及杜林图直观分析方法，通过引入浓度火积的概念及火积耗散分析，给出了热湿循环系统火积效率表达式。基于火积分析，建立了统一适用于开式和闭式溶液热湿循环显热与潜热传递能力损失的分析与优化方法。针对燃气锅炉烟气中含水量高，往往需要热湿处理过程进行潜热回收这一特点，本课题通过建立的热湿循环显热与潜热传递能力损失的分析方法，构建了烟气余热回收热湿循环流程，提出了新的烟气除湿余热回收系统并搭建了实验台进行性能测试，实验结果表明，热网回水温度高达52.5℃时，锅炉热效率提升9.1%，且最终排烟相对湿度仅为60%。针对不同工质进行了实验研究，采用甲酸钾溶液构建系统并进行优化，同时得出高湿工况下吸收器的传热传质规律。.本课题研究成果兼具理论意义与实际应用前景，基于溶液浓度火积的分析方法可普适于开式与闭式溶液热湿循环，等效T-Q图和杜林图分析方法简单直观，基于理想循环分析方法提出的烟气除湿余热回收系统可有效应用于天然气锅炉的余热回收和环境治理。