Experimental Study of a Small-Size Vacuum Insulated Water Tank for Building Applications

Abstract

Insulation of thermal energy storage tanks is fundamental to reduce heat losses and to achieve high energy storage efficiency. Although water tanks were extensively studied in the literature, the enhancement of the insulation quality is often overlooked. The use of vacuum insulation has the potential to significantly reduce heat losses without affecting the dimension of the storage system. This paper shows for the first time the results of the heat losses tests done for a 0.535 m3 water tank for residential building applications built with a double wall vacuum insulation. The different tests show that the rate of heat losses strictly depends on the temperature distribution inside the tank at the beginning of the experiment. Compared to a conventional water tank insulated with conventional materials, the U-value of the lateral surface was reduced by almost three times (from 1.05 W/K·m2 to 0.38 W/K·m2) using vacuum insulation. However, the bottom part, which is usually used to place the support parts and the piping, is the critical design part of those tanks acting as a thermal bridge with the ambient and enhancing heat losses.

Solar-Driven Sorption System for Seasonal Heat Storage under Optimal Control: Study for Different Climatic Zones

“…For the validation, just five nodes along the tank were considered, obtaining an average error of 2.1%. More information about the set-up and the water tank can be found at [32].…”

“…For the validation, just five nodes along the tank were considered, obtaining an average error of 2.1%. More information about the set-up and the water tank can be found at [32]. The control policy of the system required the instant temperature values at the top and middle part of the water tank, which corresponded to the regions intended for DHW and SH, respectively.…”