The long exposure of workers to hot and humid environments increases their discomfort and exposes them to excessive sweating, affecting their performance. Comfortable cooling vests are potential solutions to increase the productivity of the workers. This study suggests a vest that cools the back based on the indirect evaporative cooling technique, the Maisostsenko cycle (M-cycle), under which the air is cooled sensibly before it is evaporatively cooled. The cooling performance of the suggested vest is compared to a control vest that is based on the direct evaporative cooling technique. Computational models of the two vests are developed and verified by conducting experiments at 36 ± 0.5°C and 43 ± 2percent on a heated plate, providing a constant heat flux. The simulations and the experiments showed that the M-cycle cooling technique extracts more moisture than the direct evaporative cooling one. The mathematical models of both cooling techniques were then coupled with a validated bioheat model which allowed studying the human thermal and comfort responses to the proposed designs. Ambient air conditions and the activity level served as input to the computations that will predict the back torso skin temperature and overall thermal comfort under the two vest designs. The results showed that the M-cycle vest would indeed lead to a lower back temperature by a maximum of 1.27°C, and better thermal comfort for the wearer by a maximum of 38percent. This improvement in thermal comfort was more noticeable at higher ambient temperature of 45°C and lower ambient relative humidity of 18percent.
Description:
Thesis. M.E. American University of Beirut. Department of Mechanical Engineering, 2018. ET:6878.
Advisor : Dr. Kamel Abou Ghali, Professor, Engineering ; Members of Committee : Dr. Nesreene Ghaddar, Professor ; Dr. Ali Tehrani, Assistant Professor, Chemical Engineering.
Includes bibliographical references (leaves 40-43)
