Improving work efficiency and thermal comfort by negative vertical temperature gradient in heating model of impinging jet ventilation

¹ Xi’an University of Architecture and Technology, China.
² Tianjin Chengjian University, China.

^* Corresponding author: yangbin@xauat.edu.cn

Abstract

In heating model, impinging jet ventilation (IJV) supplies warm air jet with high momentum which impinges and spread over floor. Thermal stratification in opposite direction (temperature of foot area is higher than head area.) is found in the area near supply opening, because high residual momentum of the jet after impinging can resist thermal buoyancy in a considerable distance on floor surface. Negative vertical temperature gradient was seldom explored. To study how negative vertical temperature gradient affects local thermal comfort and work performance, 16 subjects (8 males and 8 females) were asked to work in a room with three negative vertical temperature gradients (1, 3, 5k/m) between head (1.1 m) and ankle levels (0.1 m). In this study, overall thermal sensation, local thermal sensation of body segments and work performance were collected. The results show that work performance and thermal comfort could be improved by higher negative vertical temperature gradients.