Simulation of hydraulic jump to detect heat dissipation for 2different ambient temperatures

Abstract

Hydraulic jump has been a very interesting topic of study for its wide application in industries and environmental engineering. A lot of work regarding its capability of energy dissipation and aeration has been conducted in past and with the advent of several simulation softwares, several attempts are being made successfully to simulate the phenomenon. Modern society is heavily dependent on power plants and a wide range of industries that in turn discharge thermally polluted water into the water bodies like canals, rivers, and lakes. The hydraulic jump could be an efficient and economic means of dissipating heat from the water discharged from the power plants and other industries. However, this topic has not been extensively studied. The present study attempts to simulate a hydraulic jump in a simple rectangular flume and determine the capability of the hydraulic jump to enhance the dissipation of heat from the water to the ambient. The inlet water temperature was kept constant at 40ºC while six different ambient temperatures were considered – 10ºC, 15ºC, 20ºC, 25ºC, 30ºC and 35ºC. The hydraulic jump for each of the ambient temperature was simulated and the drop in average temperature at a section downstream of the jump was determined. Drops in average specific entropy and average specific enthalpy were also determined and these drops in average temperature, specific enthalpy and specific entropy, for each ambient temperature, were compared with the drop in the corresponding quantities due to natural convection and conduction without the occurrence of hydraulic jump. The heat transfer from the water to the ambient aided by hydraulic jump resulted in an improvement in the drop in temperature, specific entropy, and specific enthalpy as compared to the drops in these quantities owing to heat transfer due to convection and conduction without the hydraulic jump. This improvement showed a non-linear variation with the ambient temperature and decreased with the increase in ambient temperature. However, for establishing the exact relationship between this enhancement of drop in temperature, specific enthalpy, and specific entropy by hydraulic jump with the ambient temperature and also the water temperature, a few more simulations with different water temperatures and with few more ambient temperatures have to be performed.