Combined Material and Process Development for Efficient Adsorption Heat Pumps

传统热泵的运行使用了高品位的电能，用于加热和冷却。利用太阳能、地热能或工业废热的热驱动吸附热泵是一种有趣的替代方案。吸附式热泵的特点是固体吸附剂的负载和再生之间的循环变化，以及在三个温度水平之间的操作。高热效率的条件是：1）所使用的吸附剂必须具有高的吸附能力和相对于整个过程的快速吸附动力学。该材料应具有高的内表面（微孔）和通过足够数量和排列的输送孔（大孔）的良好可达性。2)为了确保吸附剂的快速加热和冷却，吸附剂的热导率应该高以实现快速和完全的温度变化。3)吸附剂（和吸附物）被周期性地加热和冷却。整个过程的一个目标是使这种热负荷损失最小化。除了2）中提到的问题之外，这可以通过最小化吸附剂的热容量和减少惰性物质或在吸附剂和热载体的模拟逆流中使用多个模块的过程控制来实现，这导致存储热量的内部回收。4)吸附剂和相变区（冷凝器/蒸发器）之间吸附物流的传递阻力最小化。可以单独优化上述每个要求，但不能同时优化所有属性。例如，一方面可以通过添加导电材料来实现吸附剂的高导热性，另一方面这降低了吸附能力。单一材料性质的影响还取决于有利的整体工艺：具有高内部热回收的工艺（模拟逆流工艺）的效率比简单的两床工艺对惰性物质的敏感性低。到目前为止，材料和工艺开发是相互独立进行的。材料开发的目标主要是任务1）和2），而工艺技术开发（3）和4））通常基于给定的和不受影响的材料的假设。由于所描述的相关性，可以假设这种方法不会导致材料和工艺的共同最佳化。在提交的项目建议书中，两种开发应协同进行，以确定材料和工艺的理想组合，并示范性地得出材料和工艺技术设计组合的方法。

Exergetically high-grade electrical energy is used for the operation of conventional heat pumps for heating and cooling purpose. Thermally driven adsorption heat pumps using solar thermal power, geothermal power or industrial waste heat are an interesting alternative. Characteristic for adsorption heat pumps is the cyclic change between loading and regeneration of the solid adsorbent, and the operation between three temperature levels. Conditions for a high thermal efficiency are: 1) The adsorbent used has to have a high adsorption capacity and - relative to the whole process - fast sorption kinetics. The material should have a high inner surface (micro pores) and good accessibility through an adequate number and arrangement of transport pores (macro pores). 2) To ensure fast heating and cooling of the adsorbent the thermal conductivity of the adsorbent should be high for a fast and complete temperature change. 3) The adsorbent (and the sorbate) are heated up and cooled down periodically. One goal of the overall process is to minimize such heat charge losses. This can be achieved - in addition to the issues mentioned in 2) - by minimizing the heat capacity of the adsorbent and reduction of inert masses or a process control with multiple modules in a simulated countercurrent flow of adsorbent and heat carrier which leads to an internal recovery of stored heat. 4) Minimization of transfer resistances of the sorbate flow between adsorbent and phase change zone (condenser/evaporator). It is possible to optimize each of the aforementioned requirements taken in isolation, but not all properties simultaneously. For example, on the one hand a high thermal conductivity of the adsorbent can be achieved through the addition of conductive materials which reduces the adsorption capacity on the other hand. The influence of single material properties also depends on the favored overall process: the efficiency of a process with high internal heat recovery (simulated countercurrent process) is less sensitive against inert masses than a simple two-bed process. Material and process development is carried out independently of each other so far. Goals of material development are mainly at tasks 1) and 2) while the process technology development (3) and 4)) usually acts on the assumption of given and not influenceable materials. As a result of the described dependencies it can be assumed that this approach does not result in a common optimum of material and process. In the submitted project proposal both developments shall be brought in synergy to identify an ideal combination of material and process and exemplarily derive a methodology of combined material and process technology design.