نورا عبدالواحد هاشم الخالدي

Abstract. An experimental test rig is constructed and designed according to the results obtained from a thermodynamics model solves by EES software assuming a constant generator, condenser, absorber, and evaporator temperatures to study a bubble pump’s performance solar absorption cooling system. The whole system consists of a parabolic trough solar collector, a generator, a condenser, an absorber, an evaporator, and a cooling water system. The used PTC area is designed according to the quantity of thermal energy required to operate the bubble pump cooling system and the minimum solar radiation incident at Kufa city (Najaf/Iraq), which lies on (32°N and 44°E). A modification is added to the collector receiver to ensure water exposure to solar energy for a longer time. The weather features that affected system performance like the solar radiation incident and the ambient temperature are measured for each test. The maximum recorded receiver temperature is 122 ℃ without water flow, and it is reached to 90.5℃ as a maximum in case of water flow through the receiver. The water in the storage tank is reached to 89℃ as a maximum. The collector thermal efficiency reaches its maximum value of 69.2 % for a water flow rate of 0.3315 kg/s, while the maximum efficiency at 0.189 kg/s is 68.3%. The maximum recorded generator temperature is 87℃, and at the same test, a minimum evaporator temperature of 17℃ is

Abstract: A comparative study between two solutions which they usually work as a working pairs in pumpless absorption cooling system is achieved analytically with aid of ESS (Engineering Equation Solver) 9.43 software. The pump in this system is replaced by a vertical pipe (lift tube) to ensure the pressure difference between the condenser and the evaporator. These working pairs are Lithium Bromide-Water and Lithium Chloride-Water. The study intends Iraqi summer weather as an ambient circumstances. A thermodynamics model is designed to find the energy and Energy loss in each of system components. By solving the thermodynamic model, and assuming the same generator, absorber, condenser and evaporator temperatures in each case. It’s found that the system coefficient of performance is relatively the same while the probability of agglomeration in case of Lithium Bromide-Water system is higher because of the large salt concentration. It’s concluded that the Lithium Chloride-Water is most suitable in Iraqi circumstances in spite of high values of total energy loss which is obtained in case of Lithium Chloride-Water system if it is compared with the energy loss value in case of Lithium Bromide-Water system. (PDF) A COMPARATIVE STUDY ABOUT LITHIUM BROMIDE-WATER AND LITHIUM CHLORIDE-WATER SOLUTIONS IN PUMPLESS ABSORPTION SOLAR COOLING SYSTEMS IN IRAQI CIRCUMSTANCES. Available from: https://www.researchgate.net/publication/343816650_A_COMPARATIVE_STUDY_ABOUT_LITHIUM_BROMIDE-WATER_AND_LITHIUM_CHLORIDE-WATER_SOLUTIONS_IN_PUMPLESS_ABSORPTION_SOLAR_COOLING_SYSTEMS_IN_IRAQI_CIRCUMSTANCES [accessed Dec 13 2020].

An analytical energy and availability study of pump less LiBr-H2O solar absorption cooling system is submitted with the aid of ESS 9.43 software. The system consists of many components: generator vessel attached by lift tube and a separator, condenser, evaporator, solution heat exchanger, and absorber. Each component assumed to be operated at constant temperature. The effect of temperature change for each component on cycle performance as well as the availability loss are discussed. The results show that the maximum availability loss occurs during absorption process in the absorber, and the second worse component is the generator. The optimal generator temperature is obtained, and it can be proved that this system can be driven with relatively best performance at low heat sources like solar or any other waste heat sources. By increasing the evaporator and the generator temperature lower than optimum, COP and reversible COP increase while COP values decrease in case of increasing of absorber and condenser temperatures. The total availability loss increases, and the second low efficiency decreases in case of increase in all system components. (PDF) ENERGY AND AVAILABILITY ANALYSIS OF PUMP LESS LiBr-H2O SOLAR ABSORPTION COOLING SYSTEMS. Available from: https://www.researchgate.net/publication/334429877_ENERGY_AND_AVAILABILITY_ANALYSIS_OF_PUMP_LESS_LiBr-H2O_SOLAR_ABSORPTION_COOLING_SYSTEMS [accessed Dec 13 2020].

Two-phase flow pattern, pressure drop, and void fraction in vertical transparent pipe of 0.0254 m internal diameter and 3.65 m length is investigated experimentally. The rig is designed to achieve the measurements of pressure drop and void fraction for different combinations of phase superficial velocities such that the regimes encountered are bubbly, slug and annular, which required a wide range of water and air superficial velocities. The flow patterns are investigated by recording video movies for each test achieved. The pressure is measured by using five pressure sensors distributed through the pipe, while the void fraction values are measured by using two quick closing valves at pipe terminals. The effect of heating liquid to 60C˚on the pressure drop values is also discussed. The results are compared with many pressure drop and void fraction correlations. The pressure drop results in bubbly flow regime are nearest to the Lockhart and Martinelli correlation with an average difference of 3.93 %., while in slug and annular flow regimes the results are well predicted by Steinhagen and Heck correlation with an average difference of 18.4 % and 26%. Hughmark correlation is the nearest to the void fraction results in bubbly flow regime with an average difference of 2.4% ,while Chisholm and Smith correlations are the best in slug and annular flow regimes with an average difference of 6.91% and 1.71% respectively

The present study considered an impingement jet using hybrid nanofluid CuO–Cu/water. A single rounded nozzle was used to impinge a turbulent coolant (water) on the hot circular plate at Reynold’s number range of (5,000–15,000). CuO–Cu nanoparticles were physically synthesized at 50 nm size and dispersed by one-step preparation method. The experimentations were conducted with nanoparticle concentrations range of (0.2–1%) by volume. The results showed that the presence of hybrid nanoparticles exhibits a significant improvement in the overall thermal performance of the working fluid. Where the gained heat interpreted by the Nusselt number was found to be 2.8% (in comparing with deionized water) at ϕ = 1% and Re = 15,000, while the minimum gain in the heat was found to be 0.93% at ϕ = 0.2% and Re = 5,000. Furthermore, it was noted that the excessive increase in CuO–Cu nanoparticle concentration causesmore pumping power consumption. Moreover, the CuO–Cu nanoparticles residual layer was found to be formed at a high CuO–Cu concentration, which acts as an insulation layer that hinders the heat exchange. It was also found that the threshold of nozzle-to-plate spacing is H = 4, before which, the heat gain is positive, and negative plummet after.

Solar energy is one of the most efficient forms of renewable energy. Solar air collectors are promising utilization of solar energy. The present study used unsteady three-dimensional Computational Fluid Dynamic (CFD) analysis to investigate the heat transfer and fluid friction in solar air collectors with smooth and v-corrugation absorber plates. The studied parameters are Reynolds number, v-corrugation height, and pitch. Three Reynolds number (500, 1000, 1500) values were used with three arrangements configuration of the v-corrugation of relative heights of 0.10, 0.16, and 0.23. Roughness pitches varied between 1.33, 1.66, and 2. By comparing the simulated thermal efficiency with the currently known experimental values, great agreement can be approved. Results show the superiority of the performance of v-corrugated collector against the traditional or smooth type. The outlet temperature obtained in case of relative roughness height = 0.23 and relative roughness pitch = 2 is 61 °C, while it is 53 °C for a smooth type. Also, a higher thermal efficiency of 46.7 % can be obtained compared to 33.01% for smooth type.

المشاركة بالمؤتمر الثاني للبحوث التطبيقية المقام ضمن نشاطات هيئة البحث في وزارة الصناعة المقام في 22-23 /10 /2023