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Radiative heat transfer must be considered in retail refrigerators with glass doors. Some methods have been proposed for reducing radiative losses, like usage of double glased windows filled with argon or other types of transparent material with low emissivity in infrared band. For evaluation of thermal radiation in commercial refrigerator compared to infiltration loss, thermal conduction and facilities loss, a three dimensional model has been developed. In this model all wall surfaces are isothermal and evaporator with specific temperature located in roof. The radiative properties of glass are considered as actual. The results show that decreasing internal temperature of cabinet incentive radiation losses. These losses are almost independent of window surface temperature. Increasing of emissivity factor of evaporator, causes increasing of thermal radiation flux of evaporator which can be used in design improvement. Radiation flux of each surface have been compared with convection flux. This comparison show the importance of covering windows in unutilized times.

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Abstract- In this paper, numerical solution of beta-type Stirling engine was presented considering its non-ideal regenerator. To this end, the second-order model including thermal and hydraulic losses of regenerator was used and their effect on the output power and efficiency of the engine was obtained. Then, a numerical code was used for calculating dimensional and functional optimum values of regenerator. To confirm the obtained result, the functional and geometrical parameters of the engine made by General Motors Corporation called GPU-3 were used. According to the obtained results, the values of hydraulic and thermal losses in the regenerator were considerable and led to the decrease in the engine power and efficiency by 23% and 8%, respectively. Using the obtained results and numerical code, the amounts of porosity, frequency and length of the regenerator were suggested as less than 0.7, 35 Hz and 24 mm, respectively, in the optimum physical and geometrical conditions of the engine.

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In-Situ Combustion (ISC) is one of thermal heavy oil recovery methods in which the heat required to displace crude oil is generated by combustion of a small fraction of oil inside the reservoir. Because of presence of several processes such as combustion, phase change and reservoir fluids thermal expansion, in-situ combustion is regarded as a very complicated recovery method. In the present work, aiming acquiring a better understanding of ISC physics, the oil in place volume (expressing in terms of oil saturation) effects on performance of ISC is numerically investigated in 1D. In order to increase the model accuracy, a semianalytical model is used to account for heat loss to overburden and underburden. The numerical results show in reservoirs with high initial oil saturation, the mobilized oil is deposited in region near to production well during first days of ISC operation. Consequently, relative permeability of porous reservoir for gas phase considerably decreases. Moreover, combustion front propagation velocity reduces and the reservoir pressure significantly increases in the region upstream of the combustion front. As a result of the front velocity decrease, oil recovery rate decreases. Furthermore, if the pressure increasing is not considered in designing the air injection system, the air injection rate will be decreased and can lead to combustion front quenching. The results also show ignoring heat loss from the reservoir will lead to incorrect prediction of pore blockage.

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