A reduction in weight and cost of a domestic hot water
storage vessels is an interesting case for the industry, that can be
reached by an alternative material of the helical coil heat
exchanger inside them. The goal of the present study was to
design a fully polymer solar boiler demonstrator and to explore
its thermal performance in the low pressure and low temperature
conditions. The metal coil of the conventional solar boiler for
domestic usage was replaced by a plastic tube and the heat
transfer behavior of helically coiled smooth plastic tube heat
exchanger was investigated experimentally. The heat exchanger
is placed in the middle of the tank in two parallel coils that fill
almost whole height of the vessel in order to achieve maximal
surface area. The water inside the tank was heated by circulating
in closed loop with heater to achieve constant initial temperature
across the whole volume of the vessel. When reached, the
heating was stopped and a cold water of the tap temperature
started to flow inside the polymeric tube. All the required
parameters like inlet and outlet temperatures of tube-side and
stratified temperatures in fifteen different points, flow rate of
fluids and pressure drop were measured using appropriate
instruments. The test runs were performed for different initial
temperatures inside the tank ranging from 30-60°C from which
the overall heat transfer coefficient and thermal resistances were
calculated. The validity of obtained results was compared with
the numerical simulation and the experimental results on the
initial metallic tube.Papers presented at the 13th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Portoroz, Slovenia on 17-19 July 2017 .International centre for heat and mass transfer.American society of thermal and fluids engineers
