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Simulation study of a solar adsorption refrigeration system using a wing type compound parabolic concentrator (CPC) is presented. The system consists of the wing type collector set at optimum angles, adsorption bed, a condenser and a refrigerator. The wing type collector captures the solar energy efficiently in the morning and afternoon and provides the effective temperature for a longer period of time compared to that achieved by a linear collector. The objectives of the study were to evaluate the system behavior, the effect of wing length, and to compare the performance of the systems with wing type and linear CPCs. A detailed dynamic simulation model was developed based on mass and energy balance equations. The simulation results show that the system performance with wing type CPC increases by up to 6% in the summer and up to 2% in the winter, compared to the performance with a linear CPC having same collector length. The ice production also increases up to 13% in the summer with the wing type CPC. This shows that the wing type CPC is helpful to increase the performance of the system compared to the linear CPC with the same collector length and without the need for tracking.

The density of herbaceous crops creates a suitable environment to produce pathogens in the soil that intensify the attack of pathogens traditionally controlled by disinfectant, which are mostly prohibited and unlisted because of their toxicity. Grafting is an alternative technique to enhance abiotic stress tolerance and reduce root diseases due to soil-borne pathogens, thus enhancing crop production. This research study was conducted during the crop season of 2017 and 2018 in order to investigate the interactive effect of different grafting techniques of hybrid scion onto local rootstocks on plants survival, plant phenological growth, fruit yield and fruit quality under a controlled environment. The hybrid cucumber was also planted self-rooted. The cucumber (Cucumis sativus L.) cv. Kalaam F1, Syngenta was grafted onto four local cucurbitaceous rootstocks; ridge gourd (Luffa operculate Cogn.), bitter gourd (Momordica charantia L.), pumpkin (Cucurbita pepo L.), bottle gourd (Lagenaria siceraria (Molina) Standl.) using splice grafting, tongue approach, single cotyledon and hole insertion grafting techniques and self-rooted hybrid cucumber under greenhouse conditions. The experimental results indicated that all local cucurbitaceous rootstocks showed a high compatibility with hybrid cucumber scion in the splice grafting method compared to other grafting and non-grafted methods. Lagenaria siceraria rootstocks were found highly compatible with cucumber cv Kalaam scion which gave significantly maximum plant survival rates (95%) due to high sap contents, high SPAD value, better vegetative growth and maximum fruit yield when compared with other rootstocks by employing the splice grafting method followed by tongue approach, single cotyledon and hole insertion grafting while the fruit quality of all rootstocks was observed to be similar. The non-grafted cucumber cv. Kalaam F1 showed significant results of plant vegetative growth, fruit development and fruit quality and encountered grafting methods while the lowest result were associated with the hole insertion grafting method in all scion/rootstock combinations. The grafted plants have no significant effect on cucumber fruit dry matter and fruit quality while the fruit mineral compositions (N, P, K, Ca and Mg) were higher among grafted and non-grafted plant fruits. The results indicate that grafting hybrid cucumber onto four local cucurbitaceous rootstocks influenced growth, yield and fruit quality. Grafting can be alternative and control measure for soil-borne disease and to enhance cucumber production.

Solar adsorption refrigeration is promising technology especially in the developing countries and remote areas because the system can be driven by solar energy without involving electricity. Therefore, it is technologically possible and socially feasible in the areas where electricity is not enough but solar energy is rather easy to obtain. The conventional system works intermittently and produces cooling only during night. In this article, a solar adsorption refrigerator is presented that produces cooling continuously using only solar energy. The system consists of two beds with CPC collectors, a condenser and evaporator. The one cycle complete in two days. A simulation model was developed to evaluate the system performance. The objectives of this study were to investigate the dynamic behaviour of the system, and to compare the system behaviour with the conventional system. The results show that system produces continuous cooling. Cooling rate decreased in the middle of the day because of relatively high ambient temperature. The performance of the system increased with high value of heat transfer coefficient between receiver and bed, and decreased by increasing the adsorbent mass. The performance of the continuous system was compared with that of intermittent system. It was found that the evaporator temperature in the intermittent system increased during the day because cooling is not produced during day in that system, while proposed system kept the evaporator at low temperature continuously. This study will facilitate the future researches in solar adsorption continuous refrigeration technology because achieving continuous cooling only with solar energy is very attractive.

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