Direct Generation of Compressed Air from Waste Heat by Reciprocating Thermocompressors

往复式热压缩机利用废热直接产生压缩空气

• 批准号: 388388693
• 负责人: Privatdozent Dr.-Ing. Hans-Detlev Kühl
• 金额: --
• 依托单位: Lehrstuhl für Thermodynamik (TH)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/388388693?language=en
• 关键词: Direct; Generation; Compressed; Air; Waste

Compressed air is one of the most important, but also one of the most expensive technical energy sources, as the efficiency from generation to consumption is typically only about 5% due to various conversion and transmission losses. Therefore, considerable savings from both an economic and an environmental point of view can be achieved by substituting conventional compressed air generation by electrically driven compressors at least partially by other techniques, which feature a reduced or possibly zero primary energy consumption.For this purpose, the direct generation of compressed air from heat flows - preferably from waste heat - by a cascade of so-called oscillating thermocompressors is the objective of this project. The underlying principle of thermal compression has in principle been known from the Stirling cycle for a long time and was patented as "Bush Thermocompressor” in the USA as early as 1935, but has so far only been explored for a few low-pressure niche applications. It is advantageously implemented by double-acting displacer pistons that cause pressure fluctuations by periodically moving the process gas - in this case the air to be compressed - back and forth between a "hot" and a "cold" cylinder volume via a regenerator (and thus reversibly in the ideal case) at a constant overall cycle volume. By means of check valves, compressed air can thus be generated directly and very efficiently without any detours via electrical or mechanical energy, utilizing an available heat flow. In order to achieve technically usable pressure levels with such a system, a series connection of several compressor stages in a cascade is necessary. This can be achieved cost-effectively by combining units of identical design and size, despite the fact that the state variables of the air vary significantly between the inlet and the outlet pressure. As a further simplification, so-called overdriven free pistons are used, which are self-actuated without any external supply of auxiliary energy.In a first project phase, a method was developed to simulate and design one single stage of such a cascade using both analytical and numerical models. For this purpose, the theoretical principles and simulation tools mainly developed for closed regenerative gas cycles so far were transferred to this so far scarcely investigated field of open, valve-controlled cycles. Initial preliminary tests with a single, experimentally variable thermal compressor stage constructed for this purpose constitute the end of the first project phase.The aim of the proposed second project phase is to realize a cascade of several stages based on the findings of these preliminary tests. This cascade is planned to be heated and cooled with temperature-controlled heat transfer medium circuits in order to investigate and optimize the expected self-regulating properties during operation of such a cascaded machine and to compare them with the results of analytical considerations and simulations.

压缩空气是最重要的技术能源之一，但也是最昂贵的技术能源之一，由于各种转换和传输损耗，从产生到消耗的效率通常只有5%左右。因此，从经济和环境的角度来看，通过用电力驱动的压缩机取代传统的压缩空气发电，至少部分地通过其他技术来实现，这些技术的特点是减少或可能零一次能源消耗。为此目的，通过所谓的振荡热压缩机级联从热流（最好是从废热）中直接产生压缩空气是本项目的目标。热压缩的基本原理原则上已经从斯特灵循环中知道了很长一段时间，早在1935年就在美国获得了“布什热压缩机”的专利，但到目前为止只探索了一些低压利基应用。它是由双作用置换活塞有利地实现的，该活塞通过再生器（因此在理想情况下是可逆的）以恒定的总循环体积周期性地在“热”和“冷”气缸体积之间来回移动过程气体（在这种情况下是要压缩的空气），从而引起压力波动。通过使用止回阀，压缩空气可以直接和非常有效地产生，没有任何弯路通过电能或机械能，利用可用的热流。为了使这种系统达到技术上可用的压力水平，必须在级联中串联几个压缩机级。这可以通过组合相同设计和尺寸的单元来经济有效地实现，尽管空气的状态变量在进口和出口压力之间变化很大。作为进一步的简化，所谓的过度驱动自由活塞被使用，它是自驱动的，没有任何外部辅助能量的供应。在项目的第一个阶段，开发了一种方法来模拟和设计这种级联的单个阶段，同时使用解析和数值模型。为此，迄今为止主要为闭式再生气循环开发的理论原理和仿真工具被转移到迄今为止很少研究的开式、阀控循环领域。为此目的而建造的单个实验可变热压缩机级的初步初步测试构成了第一个项目阶段的结束。拟议的第二个项目阶段的目的是根据这些初步测试的结果实现一系列的几个阶段。为了研究和优化这种级联机器在运行过程中预期的自调节特性，并将其与分析考虑和模拟的结果进行比较，计划使用温度控制的传热介质回路对该级联进行加热和冷却。