Cooling load reduction through the use of stratification techniques in high bay industrial buildings

Air conditioning of the work place is essential to health, comfort, and productivity. In an effort to reduce the cost of industrial air conditioning systems, some designers have tried to design systems that utilize the principle of thermal stratification. In these systems the building is usually divided into two horizontal zones. The lower zone, ten feet above the floor, is cooled while the upper zone is not. Three systems designed for stratification were tested and found not to produce the cooling load savings anticipated.; The thesis here is that two phenomena caused the poor performance. The first phenomenon is the fact that a supply diffuser or register acts as a low velocity jet and induces air into the primary air stream from the upper hot volume of the plant as well as the lower cool volume. The second phenomenon is that a return opening draws air from the center of a sphere and so pulls as much air from the upper volume as from the lower. Based on these concepts the objective of this research is to determine whether alternative designs can achieve the desired stratification.; The first phase of the research tested, in a one third scale chamber, various locations of supply and return grilles to see which combination created the greatest stratification. A combination supply-return device was found to create the largest difference in temperature from floor to ceiling while maintaining the lowest temperature in the lower level. This device was next tested in one room in an 18 foot high building using as control an identical room using normal thermal stratification techniques. The test room used from 30 to 50% less energy than the control room. Smoke tests showed that the supply-return device created a horizontal curtain of air which caused all of the return air to be drawn from the cool lower volume of the room.; In the third phase, the use of radiant cooling panels was tested in the chamber and their performance compared to the supply-return device. Radiant cooling panels were found to perform 8% better than the supply-return units.; A computer program which predicts the amount of stratification was written and is included. The program was tested against the test chamber data with good results.