1 NEBRASKA MODIFIED ROOF POND: 1985 SUMMER PERFORMANCE RESULTS by

This paper reports on the results of three of the tests performed on the Nebraska modified roof pond. During the summer of 1985,? with the test room decoupled from the roof pond itself, several series of tests were initiated. The first experiment (fig. 1) was to test the overall response of the system by forcing the temperature in storage to a preset value and observe its decay / curve with ponding and spray. The second experiment (fig* 2) was similar to the first but with ponding only and no spray. Experiment three (fig. 3) observed the discharge of heat from pond with the-pump turned off, in essence a natural decay test without roof pond cooling. Net night sky radiation,, ambient air and pond temperatures, and dew point temperature were measured. The water in the roof pond was heated electrically to about 500C and then permitted to cool in various ways. With the pump on in experiments 1 and 2 the convection and evaporation losses were considerably larger than the radiative losses; at the elevated water temperatures the evaporative and convective losses were significantly higher than at the lower water temperatures; the convective-evaporative losses when ponding and ponding with spray are comparable. The losses from the system without active cooling strategies are mainly due to evaporation thru or refluxing in the cracks of the floating insulation and to convection