Analysis of coiled tube waste heat storage tank under water injection

摘要

In this paper, attempts are made to increase the heat transfer in the hot water storage tank via water injection into the storage water. With new water injection system, increasing mixing effect especially around the coiled tube was aimed. The experimental study was conducted to obtain the effect of different velocity (0.03 <= V <= 1.3), different flow pressures and different outlet hole diameters on dimensionless temperature distribution, Nusselt number and second law efficiency. The results showed, depending on the velocity, water injection into the tank provided an increase in the range of 15-60% for the Nusselt number. The highest enhancement in average Nusselt number occurred when the V = 1.3 m/s. The highest decrease in the second law efficiency was observed around 5% for the 1 mm hole diameter. In addition, the water injection method compared with air bubble injection method in the literature. The comparison indicated, average Nusselt number of the air bubble method 0.6% higher than the water injection method but second law efficiency and average dimensionless temperature 1.7% and 25.7% respectively less than the water injection method.