Theoretical selection of working fluids and experimental investigation of 3-phase oscillating heat pipes
Abstract
The need for high power thermal energy dissipation brought about the adoption of heat pipes utilizing phase change heat transfer. Oscillating heat pipes (OHPs) have the capability to transport thermal energy efficiently and effectively using thermally-excited oscillating motion in addition to phase change heat transfer. An experimental investigation of a three-phase oscillating heat pipe (3POHP) has been conducted to determine the solid phase or solute effect on the heat transfer performance. The working fluid in the 3POHP consists of water and a solute. Water can change phase from liquid to vapor in the evaporator and vapor to liquid in the condenser. The solute can simultaneously change phase from solid to liquid in the evaporator and from liquid to solid in the condenser. Using the UNIQUAC model, a number of solutes have been evaluated by determining the change in solubility index over a temperature range, dSI/dT , and several solutes such as sodium nitrate, ammonium nitrate, sodium chlorate, sodium acetate, erythritol, and urea have been selected for the solutes to be employed in the 3POHP. Considering the safety and availability, erythritol, and that ammonium nitrate (NH4NO3) were used as the solutes in the working fluid of the investigated 3POHP in the current investigation. Results show that the OHP charged with water and erythritol can enhance the heat transfer at a low concentration of erythritol. Also, the 3POHP charged with water and ammonium nitrate can significantly enhance the heat transfer at a high power input. It can be concluded that when the OHP is charged with a solute, the heat transfer performance can be enhanced.
Degree
M.S.
Thesis Department
Rights
OpenAccess.
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