MOHAMMED JASIM SALEH ALSHUKRI

This paper presents an experimental investigation to verify the thermal performance of a window-type air-conditioning system equipped with an innovative type of heat-pipe heat exchanger (HPHE). As the use of this type of heat exchanger leads to a reduction in the power consumed by the compressor. So, there is an increase in the coefficient of performance (COP) of the system which is the main measure for the efficiency of the air conditioning system. In this study, distilled water, acetone, and R-134a were selected as working fluids to fill the proposed HPHE with two various filling ratios (FR = 50% and 100%) to do the experimental investigation. The results indicated that equipping the system with the proposed type of heat exchanger gives a saving in the consumed power with (2.01, 2.195, and 1.33%) for 100% filling ratio of water, acetone, and R-134a as working fluids, respectively, compared to the regular system not equipped with the heat exchanger. Also, the results show that using innovative HPHE in the AC system led to an enhancement of refrigeration effect by about (3.5, 6.03, and 3.97%) at R134a, acetone, and water working fluids, respectively with (F.R = 100%)

In recent years, the need to reduce environmental impacts and increase flexibility in the energy sector has led to increased penetration of renewable energy sources and the shift from concentrated to decentralized generation. A fuel cell is an instrument that produces electricity by chemical reaction. Fuel cells are a promising technology for ultimate energy conversion and energy generation. We see that this system is integrated, where we find that the wind and photovoltaic energy system is complementary between them, because not all days are sunny, windy, or night, so we see that this system has higher reliability to provide continuous generation. At low load hours, PV and electrolysis units produce extra power. After being compressed, hydrogen is stored in tanks. The purpose of this study is to separate the Bahr AL-Najaf Area from the main power grid and make it an independent network by itself. The PEM fuel cells were analyzed and designed, and it were found that one layer is equal to 570.96 Watt at 0.61 volts and 1.04 A/Cm2. The number of layers in one stack is designed to be equal to 13 layers, so that the total power of one stack is equal to 7422.48 Watt. That is, the number of stacks required to generate the required energy from the fuel cells is equal to 203 stk. This study provided an analysis of the hybrid system to cover the electricity demand in the Bahr AL-Najaf region of 1.5 MW, the attained hybrid power system TNPC cost was about 9,573,208 USD, whereas the capital cost and energy cost (COE) were about 7,750,000 USD and 0.169 USD/kWh respectively, for one year. View Full-Text

This paper presents an experimental investigation of a new method of phase change materials (PCMs) integration in one or both the evacuated tube (ET) and two separated tanks adjacent to the water tank of heat pipe evacuated tube solar water heater collector (HP/ETC). In this method, the evacuated tube was filled with medical paraffin wax as thermal heat storage, while the two separated tanks were filled with paraffin wax (grade-A). Therefore, owing to the thermal isolation of the evacuated tube and PCM storage tanks, heat is efficiently accumulated and stored for a longer time. The advantage of this new method is that improved overall solar water heater performance by delayed heat release, thereby supplying hot water for a long time at high demand or when low solar intensity. Four HP/ETSCs with gravity assist heat pipe (GAHP) rigs were used for a comparative study. The first HP/ETC was equipped with PCM in its ET and two PCM storage tanks. The second and third HP/ETCs were integrated with PCM in an ET and two PCM storage tanks, respectively. While the fourth HP/ETC was considered a reference as it was left without PCM. Each heat pipe was filled with a 0.7 filling ratio of pure acetone. The tests are carried out with two different rates of water flow (i.e. 1 and 2L/h). The results demonstrate that the integration of PCM in both the ET and the separated tanks gives an efficiency improvement of 55.7%, While the integration of PCM in the ET led to an increase in the efficiency of 49.9%. Whereas the efficiency has been improved with the integration of PCM in the separated tanks by about 36.5%, compared with PCM-free reference collector.

Proton exchange membrane fuel cell (PEM-FC) aggregation pressure causes extensive strains in cell segments. The compression of each segment takes place through the cell modeling method. In addition, a very heterogeneous compressive load is produced because of the recurrent channel rib design of the dipole plates, so that while high strains are provided below the rib, the domain continues in its initial uncompressed case under the ducts approximate to it. This leads to significant spatial variations in thermal and electrical connections and contact resistances (both in rib–GDL and membrane–GDL interfaces). Variations in heat, charge, and mass transfer rates within the GDL can affect the performance of the fuel cell (FC) and its lifetime. In this paper, two scenarios are considered to verify the performance and lifetime of the PEM-FC using different innovative channel geometries. The first scenario is conducted by adopting a constant channel height (H = 1 mm) for all the differently shaped channels studied. In contrast, the second scenario is conducted by taking a constant channel cross-sectional area (A = 1 mm2) for all the studied channels. Therefore, a computational fluid dynamics model (CFD) for a PEM fuel cell is formed through the assembly of FC to simulate the pressure variations inside it. The simulation results showed that a triangular cross-section channel provided the uniformity of the pressure distribution, with lower deformations and lower mechanical stresses. The analysis helped gain insights into the physical mechanisms that lead to the FC’s durability and identify important parameters under different conditions. The model shows that it can assume the intracellular pressure configuration toward durability and appearance containing limited experimental data. The results also proved that the better cell voltage occurs in the case of the rectangular channel cross-section, and therefore, higher power from the FC, although its durability is much lower compared to the durability of the triangular channel. The results also showed that the rectangular channel cross-section gave higher cell voltages, and therefore, higher power (0.63 W) from the fuel cell, although its durability is much lower compared to the durability of the triangular channel. Therefore, the triangular channel gives better performance compared to other innovative channels. View Full-Text

The research aims to investigate the possibility of enhancing the functionality of a heat pipe evacuated tube collector (HPETC) with a new method of, one or both an evacuated tube (ET) and two separate storage tanks, incorporating nano or micro-enhanced phase change materials as a thermal energy storage system (TESS). In the proposed systems, the (ET) was filled with enhanced medical paraffin wax, while the two separated tanks were filled with enhanced paraffin wax (grade-A). These two types of paraffin wax were enhanced with 5wt% CuO nanoparticle (NP-CuO) or ZnO microparticles (MP-ZnO). In this study, Six tests were carried out to do the investigation. Three tests were done to investigate the effect of the integration of enhanced-PCM in the only (ET) of HPETC. While the other three tests performed to investigate the effect of enhanced-PCM integrated into both (ET) of HPETC and two additional storage tanks. The main advantage of this new system is that it improved solar water heater efficiency by minimizing hot water temperature fluctuations. Thereby, the efficiently thermal isolation of the (ET) and storage tanks and the efficient energy accumulation in PCM which enables the system to supply hot water even when there is no solar radiation at night or in overcast weather. The results showed that the integration of enhanced-paraffin wax with NP-CuO and MP-ZnO in both the (ET) and the separated tanks gives an efficiency improvement range of (36.8-50%) and (25.43-41.4%) respectively, While the integration of enhanced-paraffin wax with NP-CuO and MP-ZnO in the only (ET) led to an increase in the efficiency with a range of (33.8-45.7%) and (23.8-26.7%) respectively, compared with a typical reference collector without PCM. Also, the NP-CuO enhanced paraffin wax integrated with the ET gave a better improvement in the evaporation & condensation coefficients in the evaporator and condenser sections where their values were (401 and 2366.4 W/m2·°C) respectively at a flow rate of 1L/h.

An experimental research has been performed to investigate and elicit a heat pipe evacuated tube solar collector (HPET-SC) that subjected to mechanical vibration. The voltage ranges used to generate vibration frequency are 6, 8, 10 and 12 Volts. For comparison, two HPET-SC's were built identically. This comparison has been made based on the solar collector effectiveness of in a presence and an absence of the vibration under Iraq's winter climatic conditions. In this study, a liquid of an Acetone was used as a working fluid inside the heat tube with 0.7 filling ratio. One of the outlet investigation results indicates that heat transfer coefficients of the evaporation and condensation increased with increasing of the vibrational frequencies. Another result, using the controllable vibration system led to increasing the two coefficients of heat transfer, the temperature of hot water and the total collector effectiveness by (25%), (15%), and (20%) respectively throughout the test conditions.