Performance Analysis of Multi Capillary Knudsen Heat Pumps

Abstract

The present work investigates the theoretical performance of the Knudsen heat pump (KHP), a novel heat pump concept in which the conventional mechanical compressor is replaced by a Knudsen compressor. This modification has the potential to reduce both maintenance requirements and energy consumption. The flow behavior within the Knudsen compressor, the core element of the KHP, is described using a simplified gas model derived from the formulation originally proposed by Muntz et al. The model predictions are initially validated against well-established data reported in the literature, and subsequently employed to analyze the performance of the KHP, with the final objective of enhancing its operational efficiency. To ensure the practical relevance of the performance assessment, the analysis is conducted using realistic geometrical and operational parameters derived from previously reported experimental studies of Knudsen compressors featuring rectangular or circular cross-sectional geometries. The results of this study suggest that, while the original KHP configuration exhibits limited performance, parametric analysis suggests the possibility to enhance its performance by more than 100% under optimal conditions, with additional factors identified that may enable further gains.