(3) 3. Thermodynamic analysis of the vapour-pressurizing solar pump. The use of solar energy for the operation of irrigation pump is attractive in China. We have carried out the thermodynamic analysis of the vapourpressurizing solar pump which has been studied by investigators in India, the Soviet Union and other countries. Vapour-pressurizing solar pump is driven by the vapour of working substances. Only the flow work of the vapour is utilized. So, the construction of the pump is rather simple because it does not have a rotating part. Thermodynamic analysis and calculation show that when the temperature of a heat source is lower, the cycle efficiency of the vapour-pressurizing pump is cose to that of the Carnot cycle. Therefore, it is worthwhile performing research of the vapour-pressurizing pump in a small capacity. A comparison among five kinds of working substances shows that the Fil and Fl3 are more suitable for the vapour-pressurizing pump. 4. An analysis of steady state heat transfer for a conical focusing solar energy collector^4' A detailed analysis of steady state heat transfer is made for a conical focusing solar energy collector with a cylindrical glass cover around the absorber. The equilibrium temperatures under various conditions have been calculated using a computer. The influences of the diameter of the absorber, the wind speed, and the emissivity of the absorber surface on the equilibrium surface have been discussed. The calculation shows that using the selective coating and the cylindrical glass cover both are effective means to improve the thermal performance of the collector. The cylindrical glass cover can also make the collector steadier. A solar autoclave designed on the basis of this analysis has been made. The thermal performance obtained from experiment has proved that our theoretical analysis is correct. 5. Prediction of the thermal performance of the natural circulation water heater. With the increasing interest in using solar water heaters, it is important for the design engineers to present a method which can predict the thermal performance of the solar water heater to be designed. In China, the more widely used solar water heaters are those operating by natural circulation, so the mathematical modeling and simulation methods are used to show the influences of the factors on the thermal performance of such water heaters. The factors we have studied are: the distance between the collector and storage tank, the wind speed, the insulations, etc. The results of calculation are in fair agreement with those obtained by the experiment. Thus, it is believed that the modeling and simulation method is suitable for designing solar water heaters. (6) 6. Investigation on the low-cost solar radiation measuring instruments/ ' In research on the use of solar energy and solar radiation resources accurate insulation measurements are essential. A new technique for measuring the intensity of direct solar radiation at normal incidence and solar radiation from the whole hemisphere is being developed. The pyrheliometer and the pyranometer constructed by using the suggested technique will be inexpensive in comparison with the commonly used instruments produced now in China. Unlike the usual method of measuring solar radiation, the new technique consists of measur-
RkJQdWJsaXNoZXIy MTU5NjU0Mg==