Feasibility of solar hot water and distillation systems in Vietnam

This thesis studies the feasibility of solar hot water and distillation systems in Vietnam. The first part of the work involved investigating the available solar radiation data for Vietnam and developing procedures for producing hourly solar radiation and ambient temperature sequences for use in simulation studies. Two versions of the modified Angstrom formula were developed from long term records of measured monthly mean daily global solar radiation and sunshine hour values obtained from twelve meteorological stations across Vietnam. These formulae were then used to estimate solar radiation for additional stations where only sunshine records were available. The results from these two formulae were compared with those from eight other commonly used correlations between solar irradiation and sunshine duration. The distribution of the solar radiation throughout the country was then summarised in the form of monthly solar radiation maps, a useful approach for those interested in assessing the potential for the application of solar energy in Vietnam. A computer model to generate hourly solar radiation and ambient temperature sequences from monthly average daily radiation values, or monthly average daily sunshine hour data, and monthly average daily temperature values, was developed. This model can be used for a tropical country like Vietnam to overcome the difficulty of the scarcity of hourly solar radiation data for use in simulation packages. The resulting model was tested in a number of ways. A single purpose, user-friendly simulation program for solar hot water systems (SHWS) in Vietnam, called VIETSIM, was developed. This program has been validated by comparing the results of this program with those from the well-known TRNSYS program and is shown to be highly reliable. The feasibility of SHWS in Vietnam is studied for both the domestic and commercial sectors. For the domestic sector, the analysis focuses on medium size families in three locations, representing the main climatic types in this country. For the commercial sector, a case study of a hotel - office building is used as an indicator of the feasibility in this sector. The development of SOLSTILL, a simulation program for estimating the performance of basin type solar stills is described. Models for both the standard free convection solar still and a forced convection solar still with enhanced heat recovery were included in the program. The design, fabrication and testing of an experimental system set up at Murdoch University Energy Research Institute to validate SOLSTILL is detailed. The comparison of experimental and simulation results indicates that the program can predict distillate production at an acceptable level of accuracy. The results from a sensitivity analysis of SOLSTILL involving varying weather, design and operational parameters are also presented. The feasibility of such solar distillation applications in Vietnam is investigated through the use of the SOLSTILL program in a case study