Energy Performance Of Thermoelectric Ceiling Radiant Panels With A Dedicated Outdoor Air System In High-Speed Train Cabins

Abstract

This study aims to investigate the energy performance of thermoelectric radiant panel (TERP) with a dedicated outdoor air system (DOAS) for use in high-speed train cabins. The DOAS treats the latent loads of the cabins and operates as a 100% outdoor air ventilation system. The selected DOAS consists of a cross-type membrane heat exchanger, a direct expansion coil, and an electric heating coil. Sensible heating and cooling loads are accommodated using TERP. A thermoelectric module (TEM) is a solid-type heat pump without refrigerant, and therefore it can operate for radiant cooling and heating by simply inverting the direction of the input current. The TERP consists of an aluminum panel, TEMs, thermal insulation, and heat fins for heat exchange. The heat fins were installed to be exposed to the outside air, and therefore, the heat rejection and absorption could be achieved based on the air flowing on the surface of the high-speed train. This decoupling concept of ventilation and air-conditioning functions can prevent cross-contamination and increase the air quality. In addition, the TERP in a high-speed train was expected to reduce the operating energy owing to the free cooling and heating from the outside air without fan operation. In this study, detailed energy simulations were conducted to compare the energy saving potentials of the proposed system compared with a variable air volume (VAV) system. An empirical model for the chiller, a semi-black box model for the TEM, and mathematical models for other equipment were used to predict the performance of each component. The Korean train express from Seoul to Busan in South Korea was selected for thermal load calculation using TRNSYS, and an annual simulation was conducted. As a result, the proposed system showed a total system energy savings of 30% annually compared with the conventional VAV system.