The comparative field performance study of heat pipe evacuated tube collectors with standard design manifold header and parallel flow manifold header based on the metal foam structural element

Abstract

The paper deals with an experimental thermal performance comparison of standard design heat pipe evacuated tube collector and collector with parallel flow manifold header with metal foam structural element which was developed by authors in their previous work. The used data were obtained during experimental simultaneous operation of two interconnected solar systems at the Centre of Renewable Energy Sources, Kosice, Slovakia during the months of April and May in various weather and climatic conditions. Manifold header with metal foam structural element partially eliminates deficiencies of standard design manifold headers by changing of heat transfer medium stream conducting to each condenser, reducing the internal fluid volume and introducing of new structural element to manifold header design – heat exchange chamber made of metal foam which increases the heat exchange surface of condenser. Presented data consist of a selection from all measurements taken during experimental operation, when solar collector with manifold header based on metal foam showed a performance increase around 25%, and reduced thermal inertia of the solar collector at operation with changing intensity of solar insolation, which leads to an overall improvement in function of the solar system.