Inverse design tool for rotary positive displacement machines with liquid injection

该项目的目标是开发一种工具，用于在腔室模型模拟的基础上，对液体喷射的旋转正位移机器（例如双螺杆机器、旋转叶片机器）进行逆向设计，该工具将提供给优先计划的参与者，用于在热力学循环（压缩机或膨胀机）中对流体能机器进行建模。反设计工具的输入参数是所选工艺的要求，即除了流体的类型和质量流量外，RPDM的进口端口，注射喷嘴和出口端口的流体条件（例如压力，温度，蒸汽质量）。反求的设计参数是机床的几何形状和转速。在工具内，针对能量效率进行了优化设计参数。机器几何结构的优化不仅限于机器尺寸，还包括RPDM的特定无量纲几何参数（如内置体积比、包裹角、直径与长度比），特别关注流体依赖性。RPDM设计的关键因素是正确确定流体相关效应，如两相间隙质量流率、由于蒸发或冷凝引起的热传递以及机器进出口端口的节流效应。概述的目标与各种科学挑战有关。一方面，它需要为RPDM自动生成腔室模型。需要将几何图形抽象为容量（例如体积、机器部件）及其连接，以便交换质量和/或能量。此外，还需要质量和能量交换的有效模型（例如，通过间隙或阀门/开口的多相流，相变和传热模型）。在这方面，该项目的一个重点将是为注入液体（工作流体或辅助流体，如油的质量流量）进入RPDM工作腔室的影响建立有效模型。本文对射流的时间发展、旋转工作室内液体的随时间分布以及气液两相的传质传热等问题进行了研究，并采用通用的实验装置进行了数值模拟。对于卡诺电池，通过注入液相来调整RPDM出口温度以满足工艺温度要求的可能性-同时保持机器的最佳压力比-似乎是有利的。

The objective of the project is to develop a tool for the inverse design of rotary positive displacement machines (RPDM) (e.g. twin-screw machines, rotary vane machines) with liquid injection on the basis of a chamber model simulation, which is provided to the participants of the Priority Programme for modelling the fluid energy machine within thermodynamic cycles (compressor or expander). Input parameters for the inverse design tool are the requirements from the selected process, i.e. in addition to the type of fluid and the mass flow rates, the fluid conditions at the inlet port, injection nozzle and outlet port of the RPDM (e.g. pressure, temperature, vapour quality). The design parameters to be inversely determined are the machine geometry and the speed. Within the tool the design parameters are optimized with regard to energetic efficiency. The optimization of machine geometry is not only limited to machine size, but also includes specific dimensionless geometric parameters of RPDM (e.g. build-in volume ratio, wrap angle, diameter to length ratio) with particular focus on the fluid-dependency. Crucial factors in the design of the RPDM are known to be the correct determination of the fluid-dependent effects, such as the two-phase gap mass flow rates, the heat transfers due to evaporation or condensation, and the throttling effects in the inlet and outlet ports of the machine. The outlined objective is associated with various scientific challenges. On the one hand, it requires an automated chamber model generation for the RPDM. Abstraction of the geometry into capacities (e.g. volumes, machine parts) and their connections for exchange of mass and/or energy is needed. Furthermore, valid models for the exchange of mass and energy between the capacities are required (e.g. multiphase flows through gaps or valves/openings, phase change and heat transfer models). In this respect, one focus of the project will be the development of valid models for the effects of an injected liquid (mass flow rate of the working fluid or an auxiliary fluid, e.g. oil) into the working chambers of the RPDM. Questions about the temporal development of the liquid jet, the time-dependent distribution of the liquid in the rotating working chambers and the mass and heat transfer between gas and liquid phases are taken up and investigated experimentally using a generic test rig and accompanying numerically. With respect to the Carnot battery, the possibility to adjust the outlet temperature of the RPDM to a temperature requirement for the process by injecting a liquid phase - while maintaining an optimal pressure ratio for the machine - appears to be advantageous.