This work aims to produce an experimental and theoretical analysis of thermal insulator specifications for buildings with sustainable requirements. In the experimental work, three categories of thermal insulators were prepared from composite materials, and each category had ten models. These composites included the addition of two types of waste (sawdust and tyre waste) as fillers for two types of matrices (liquid polyurethane and polyurethane foam) to obtain composite materials for thermal insulation samples. The prepared samples were subjected to tests to show their thermal properties, such as thermal conductivity and specific heat capacity as well as undergoing a hardness test. The theoretical analysis included the discovery of empirical equations for thermal properties as functions of two variables (temperature and mass ratio) and hardness as a function of one variable (mass ratio). A genetic algorithm optimisation technique was used to find the optimum mass ratio of the composite that produced the required insulation specifications. The results showed that thermal conductivity decreased when the sawdust mass ratio and the rubber waste mass ratio increased but remained under the thermal insulation range. Furthermore, the prepared insulator samples showed an improvement in thermal storage and the hardness of tyre waste (liquid polyurethane composites) and sawdust (polyurethane foam composites). Finally, optimum results were obtained using the optimisation technique.
The present work includes a study on the effect of loading rubber waste into cement mortar on the thermal and mechanical properties of a thermal insulator.The experimental work of the study included the preparation of ten models of 35 mm diameter and 5 mm thickness. Portland cement and natural sand were used as a matrix and rubber waste (extracted from the consumed tires) as a filler was added in weight percentages ( 5% ,10% ,15% ,20% ,25% ,30% ,35% ,40%,45% and 50%). Water was also used as a binder.Also, the experimental work included conducting a thermal conductivity test using Lee’s Disk method, and a hardness test using the Shore scale. The theoretical side included extraction of empirical equations, depending on the experimental results. The thermal conductivity equation was for two variables, temperature and mass fraction. While the hardness equation was for one variable, mass fraction. Theoretically determined heat capacity was extracted using the equations of the composites. Based on the empirical equations of thermal conductivity and hardness and using the technique of multi-objectives genetic algorithm, the optimum values of temperature and mass fraction were extracted, which achieve the best thermal insulation of the mortar.The results showed a significant decrease in thermal conductivity. The reduction in thermal conductivity was (90.3%) at 5% and reduced to (95.73%) at 50%. The specific heat capacity was increasing as the percentage of rubber waste increase. The results also indicated a decrease in hardness. The optimal value of thermal insulation was (0.02658 W/m2.ºC ) as a thermal conductivity and (58.07 N/m2) as a hardness, at temperature (50°C) and mass fraction (27.764%) of rubber waste.Index Terms— rubber wastes ,empirical data , genetic algorithm.
This paper presents an experimental study to enhance the flow and heat transfer enhancement over horizontal and orientation channel with hot base by laminar mixed convection heat transfer. The hot base is fitted with the longitudinal rectangular fin arrays as a finned wall. The study covered the following range: modified Grashof number varied (3× 101 - 8× 108), Reynolds number in range 1800-2300, and Pyrantel number 0.71. The bottom finned wall of the channel was supplied with constant heat flux, while the other sides are insulated. The experiment part includes a suitable test rig that was built to get accurate decisions. A good mechanism was created to get the orientation angles at (90°,120°, 150 °and 180°) then to analysis this effect on heat transfer for laminar flow force convection. Three different cases are investigated: the effect of modified Grashof number and orientation angles on fluid particles flow and heat removal will be an enhancement. The experiment results show that the average heat transfer coefficient increased with Reynolds number and an increase of the Grashof number for all orientation angles due to increases buoyancy forces, thus causes a detach with the secondary layer flow. The average heat transfer coefficient and fins effectiveness are enhanced to 25% at highest longitudinal orientation angles.
The temperature of a photovoltaic (PV) module has a significant impact on the module's ability to produce electricity. PV cells module’s passive cooling is critical for increasing electrical efficiency and power output. In this work, two scenarios of the passive cooling technique were presented for use in the cooling of the monocrystalline silicon PV modules. An aluminium finned wall and a combination of aluminium finned wall with phase change material were connected to the backside of the PV in order to bring the working temperature down and maintain it under the hot climate conditions in southern Iraq. Paraffin wax was employed as a PCM placed into an aluminium container with internal and exterior longitudinal aluminium fins in order to enhance the PCM's poor thermal conductivity, speed up the rates at which it melts and solidifies, and increase the amount of heat that is dissipated through free convection heat transfer. The PV modules were simultaneously tested and compared with a PV reference module under different solar radiation. According to the findings, the average temperature of the PV-Aluminium Finned wall-PCM module is reduced by 19.9 degrees Celsius when compared with the temperature of the reference PV module. This results in an increase in the average maximum output power of up to 23.1% compared to an identical reference PV module. Furthermore, the average electrical efficiency of the PV-Aluminium Finned wall-PCM is enhanced by 23.2% during the testing time from 9:00 AM to 12:00 PM in July 2022 at maximum solar radiation of 1130.7 W/m2 when compared with the PV reference module under the same conditions. This indicates a significant increase in both electrical and thermal performance. The testing took place in July 2022.
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