Analysis and Simulation of a Two-Phase Self-Pumping Water Heater

Abstract

The thermal performance of a two-accumulator self-pumping solar water heater is characterized in a daily simulation. The passive vapor transport system operates in cycles, alternating between run, pressurizing, and pump phases. Three isothermal closed-system thermodynamic models characterize the operational phases of the system. The applicable conservation of mass and energy equations of each model are combined in the numerical simulation. Instantaneous temperature and heat transfer rates, as well as integrated energy quantities and thermal efficiencies, are compared to experimental values. The qualitative behavior of the analytical model agrees with that of the physical system. Multiplying thermal loss coefficients by 2.5 and adjusting the theoretical solar model to correspond with measured insolation forces quantitative agreement of overall daily performance. The simulation reveals the impact of the duration of the pressurizing and pumping phases on overall performance. The volume and thermal capacitance of the components used during the pressurizing and pump phases should be minimized, while the insulation on those components should be maximized to optimize system performance. The validated model will be used in future work to optimize system design.