A TRNSYS Model of a Solar Thermal System with Thermal Storage and Absorption Cooling

Abstract

A combined flat plate and vacuum tube solar thermal array on the roof of the University of New Mexico Mechanical Engineering building is used to produce hot water. The hot water fires a lithium bromide absorption chiller in the summer and flows through heating coils in the winter, providing cooling and heating respectively. To overcome problems associated with intermittent insolation, an insulated concrete tank is used for hot thermal storage. Additional concrete tanks without insulation are used to store chilled water. These cold storage tanks are used as the primary chilled water source to meet the cooling load, while the absorption chiller provides additional cooling during peak load periods. The cold storage tanks are cooled by a district chiller at night when district chilled water demand and the cost of electricity are low. TRNSYS, a transient systems simulation program with a modular structure, is used to model and predict optimal operating conditions of the solar array working in combination with the thermal storage system, absorption chiller and cooling system. This research enhances engineering education for undergraduate and graduate students at the University of New Mexico. Also, key concepts from this research are translated into standards-based middle school science curriculum.