Development of a Code for the Simulation of Absorption Refrigerating Machines

为了提高制冷机对冷负荷变化的响应能力和部分负荷特性，开发了双效吸收式制冷机的仿真程序，并对其优化运行方法进行了研究。该试验机能够连续控制能量输入和弱液流量。它由燃气高温发生器、分离器、低温发生器、吸收塔、冷凝器、蒸发器和高低温换热器组成。工作液体为溴化锂和水溶液。标准输出功率为80kW。在实验数据的基础上，建立了静态特性的仿真模型。实验和模拟分析表明，在任何给定的冷负荷条件下，都存在一个使性能系数最大的最佳弱液流量。最佳工况与…流出的制冷剂蒸汽流量密切相关由于吸收式制冷机的热容量比蒸汽压缩式制冷机大，因此在变冷负荷条件下的动态特性是一个有待改进的问题。研究了能量输入和弱液流量随冷负荷变化的控制方法。由于冷负荷和制冷量的变化是温和的，因此可以用稳态特性来估计与冷负荷相对应的最佳运行条件。如果冷负荷与最佳运行条件之间的关系是已知的，则可以采用前馈控制。本文提出了一种新的控制算法，称为多变量开环控制。与传统的冷水出口温度比例控制相比，MOL控制可以实现制冷量的平稳变化和燃料消耗的降低。较少

For the purpose of improving the response to cooling load variations and the part load characteristics, the simulation code for a double-effect absorption refrigerating machine was developed, and the optimal operation method was investigated. The test machine was designed to be able to control energy input and weak solution flow rate continuously. It is composed of a gas-fired high-temperature generator, a separator, a low-temperature generator, an absorber, a condenser, an evaporator, and high- and low-temperature heat exchangers. The working fluid was Lithium Bromide and water solution. The standard output was 80 kW. Based on the experimental data, a simulation model of the static characteristics was developed. The experiments and simulation analysis indicate that there is an optimal weak solution flow rate which maximizes the coefficient of performance under any given cooling load condition. The optimal condition is closely related to the refrigerant steam flow rate flowing from the … More separator to the high-temperature heat exchanger with the intermediate solution.Because the heat capacity of absorption refrigerating machines is large compared with vapor compression refrigerating machines, the dynamic characteristics at the change in cooling load conditions are a problem to be improved. The control method of energy input and of weak solution flow rate following cooling load variations was investigated. As the changes in cooling load and cooling capacity are moderate, the optimal operation conditions corresponding to the cooling load can be estimated with steady state characteristics. If the relation between the cooling load and the optimal operation conditions is well known, a feed forward control can be employed. In this report a new control algorithm, which is called MOL (Multi-variable Open Loop) control, is proposed. Comparing the MOL control with the conventional chilled water outlet temperature proportional control, the MOL control enables the smooth changes in cooling capacity and the reduction in fuel consumption. Less