13 Space heating and cooling tcmpcrature of 420 K. An exergy analysis was performed to study losses in differeflt components of the cycle. It is seen that the largest contribution to cycle irreversibility comes from the absorber, with the rectifier and solution heat exchanger also contributing significantly, Irreversibility generation in the boiler is high at very low heat source temperatures, but drops at higher temperatures. 03/02546 Geographic constraints on passive solar domestic hot water systems due to pipe freezing Salasovich, J. ef crl. S&r Energr. 2002, 73, (6). 469-474. The supply and return piping of passive solar domestic hot water systems (SDHWS) is typically exposed to ambient weather conditions, and damaging pipe freeze is a major concern. This paper presents a pipe-freeze mode] that accounts for hot water draws and uses 30 years of actual weather data. The simulation results are cast in terms of pipefreeze probabilities. Using contour maps of the continental United States, the pipe-freeze probabilities for residential, commercial, and seasonal passive SDHWS are presented for various pipe and insulation geometries.