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In this paper, thermal models of all types of solar collector-integrated active solar stills are developed based on basic energy balance equations in terms of inner and outer glass temperatures. In this paper, hourly yield, hourly exergy efficiency, and hourly overall thermal efficiency of active solar stills are evaluated for 0.05 m water depth. All numerical computations had been performed for a typical day in the month of 07 December 2005 for the climatic conditions of New Delhi (28°35′N, 77°12′E, 216 m above MSL). The thermal model of flat-plate collector integrated with active solar still was validated using the experimental test set-up results. Total daily yield from active solar still integrated with evacuated tube collector with heat pipe is 4.24 kg m-2 day-1, maximum among all other types of active solar stills. Copyright © 2007 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper, an attempt has been made to develop a new model to evaluate the hourly solar radiation for composite climate of New Delhi. The comparison of new model for hourly solar radiation has been carried out by using various model proposed by others. The root mean square error (RMSE) and mean bias error (MBE) have been used to compare the accuracy of new and others model. The results show that the ASHRAE and new proposed model estimate hourly solar radiation better for composite climate of New Delhi in comparison to other models. Hourly solar radiation estimated by constants obtained by new model (modified ASHRAE model) for composite climate of India is fairly comparable with measured data. The percentage mean bias error with new constants for New Delhi was found as low as 0.15 and 0% for hourly beam and diffuse radiation, respectively. There is a 1.9–8.5% RMSE between observed and predicted values of beam radiation using new constants for clear days. The statistical analysis has been used for the present study. Copyright © 2008 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper, an attempt has been made to evaluate cloudiness/haziness and atmospheric transmittance factors for the composite climate of New Delhi, India by considering the hourly data of global and diffuse radiation obtained for (i) the city region, experimentally observed and (ii) the flat land region obtained from the Department of Indian Meteorology, Pune. Cloudiness/haziness factor for the two models have been determined using simple regression analysis for clear sky condition for New Delhi. The comparison between the cloudiness/haziness and atmospheric transmittance factors for the composite climate of New Delhi for both the models and regions have been made. It has been observed that the cloudiness/haziness and atmospheric transmittance factors obtained by both models gave fair agreement within an accuracy of 0.57%. It has also been observed that there is a significant effect of region on beam and diffuse radiation due to cloudiness/haziness factors as expected. Further the data of solar radiation obtained from the Department of Indian Meteorology, Pune, have been used to evaluate the monthly performance of photovoltaic thermal (PV/T) air collector. It has been found that an overall thermal efficiency and exergy efficiency of PV/T air collector were about 50 and 14%, respectively. Copyright © 2006 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]