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• A new design of the solar still of rhombus shaped is studied using new model. • Decreasing the solar still declination angle rises the solar still performance. • Energy loss decreases with decreasing the inclination angle. • Maximum daily SS freshwater yield is 2.9 kg/m2.day in winter, 4.8 kg/m2.day in spring, and 5.4 kg/m2.day in summer. • Maximum solar still efficiency is 29% in winter, 42% in spring, and 47% in summer. A theoretical study on the performance of new design solar still of rhombus shape is presented. The rhombus solar still shape is composed of two glass cover walls of Λ shape while the still basin is of V shape including wood fibers porous material saturated with saline water. A complete new theoretical model is presented for the solar still including still basin and walls and humid air region. The radiation exchange between still walls is considered in the theoretical model. The study is performed under different climate conditions of Upper Egypt in summer, winter, and spring at different inclination angles of the still basin with the horizontal of 70°, 45o, and 30°. The theoretical model is validated with an experimental work and shows a good agreement between the theoretical and experimental results. The findings show that the solar still performance (solar still temperatures, freshwater production, and solar still efficiency) rises with decreasing the inclination angle of the solar still while the energy loss decreases with decreasing the inclination angle. The radiation exchange between the glass walls and the basin surfaces is negligible compared to the radiation exchange between the glass walls and their faced basin surfaces. The maximum daily solar still freshwater yield is 2.9 kg/m2.day in winter, 4.8 kg/m2.day in spring, and 5.4 kg/m2.day in summer while, the maximum solar still efficiency is 29% in winter, 42% in spring, and 47% in summer. [ABSTRACT FROM AUTHOR]

Highlights • New design of a solar refrigerator is proposed. • A good agreement between experiments and simulation was noticed. • Experiments show that the improvements had a good impact on the thermal performance of the solar refrigerator. • The mass of the load inside the storage box has a great influence on the performance of the refrigerator. • The initial mass of refrigerant inside the evaporator is also an important parameter to study. Abstract This work deals with a new design of a solar driven adsorption-refrigerator. The solar refrigerator uses a single bed adsorber-collector and works with silica gel/water as a sorption pair. The novelty of this work is in the use of low cost and effective techniques that permitted to palliate to the problem of days with low solar radiation. In addition to that, a model with a minimum of constraining hypothesis was proposed. The model was implemented in a MATLAB-program and showed a good prediction accuracy during several tests with different operating conditions. This paper aims to put into evidence the impact of an enhancement with four external reflectors. The influence of the mass of the load as well as the influence of the initial mass of the refrigerant are also highlighted. Tests that were effectuated in the region of Sfax-Tunisia, resulted in a maximal COP solar valuing 0.078 and a maximal cooling capacity of 777.96 kJ. The proposed refrigerator was also able to make the temperature of a 9 kg water-load decrease to reach 0 °C during a partially cloudy day. [ABSTRACT FROM AUTHOR]