According to equation (4), (8), (21) and (23), Thermosyphon performance depends on the solar pond temperature vise versa. The explanation can be done as follows, while the solar pond has low temperature, thermosyphon have a low performance. This is because of high thermal resistant inside thermosyphon. Solar pond will, later, have high temperature. Since there are heats in solar pond to be extracted, thermosyphon performance will also increase. A large amount of heat, consequently, is extracted by thermosyphon. These results in decreasing of solar pond temperature thermosyphon performance will decrease again. This situation cycle occur continuously in extraction process. As discussion above, we can see that solar pond temperature and heat extracted by thermosyphon are very with time. Detail of the time series solar pond temperature and extracted heat will be shown later.

2.3 Simulation flow chart

The general information of thermosyphon and solar pond such as geometry, location, and initial pond temperature and operation time will be input to program. When the general information already be input, the heat transfer rates for thermosyphon (Qthermosyphon) will be tried, to be used in equation (4). By numerical method, the temperature of solar pond at LCZ can be determined. Now the actual performance of thermosyphon can be determined. Comparing the trial heat transfer with values from later calculation, if they are equal then the calculation finishs, otherwise the program begins a new trial by set trial value equal to the last calculation values. The calculation will be done again until both are equal. This obtained value is the amount of heat extracted from solar pond by using thermosyphon.