Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : Thermal efficiency


Thermal Investigations of Double Pass Solar Air Heater with Two Types of Porous Media of Different Thermal Conductivity

Jalal M. Jalil; Shrooq J. Ali

Engineering and Technology Journal, 2021, Volume 39, Issue 1A, Pages 79-88
DOI: 10.30684/etj.v39i1A.1704

This study describes an experimental investigation of the thermal efficiency of stainless steel mesh and steel wool as a porous medium in the lower channel of a double pass solar air heater. An experimental setup was planned and developed. Various types of porous media with high thermal conductivity and with different porosities have been tested. The effects of the porosity of wire mesh, the thermal conductivity of porous media, mass flow rate, and the intensity of radiation have been studied. Experimental results show that thermal efficiency with using porous media is greater than without using porous media. When used steel wool as a porous medium, the thermal efficiency reached 79.82 percent while it can be achieved 76. The percent by using stainless mesh as porous material. The reduction in porosity increasing thermal efficiency. The thermal efficiency of multi-pass solar air collector when used steel wool as porous media is 6, 12.6 and31.7percent higher than without porous media at porosity 98.75, 97.5, and 96.25percent. While it can increase 8.1 and 28.5 percent at porosity 97.875 and 95.75 percent when using stainless steel as porous media.

PV/T Performance Evaluation as Electricity Generation and Hot Air Supplier for Fully and Partially Covered with PV Modules

Jalal M. Jalil; Ahmed A. Hussein; Anwar J. Faisal

Engineering and Technology Journal, 2020, Volume 38, Issue 7, Pages 1001-1015
DOI: 10.30684/etj.v38i7A.559

The solar energy system is environmentally friendly and the utilization of photovoltaic thermal collectors, (PV/T) has attracted more attention, which directly converts solar radiation into electricity and thermal energy simultaneously. This study investigated the air biased Photovoltaic thermal hybrid solar collectors, (PV/T) trend for two cases, denominate case one (PV/T system fully covered with PV modules), and case tow (PV/T system partially covered with glass). The studied parameters were solar irradiance and the air mass flow rate. The investigation has been performed in terms of outlet air temperature, electrical power, thermal and electrical efficiencies. A numerical model was developed using the computational fluid dynamic program (CFD) and the results were compared with the experimental measurements that carried out from indoor conditions using a solar simulator. A good agreement has been achieved between experimental and numerical results. The performance of both cases one and case two concluded that the PV/T system should be operating at a moderate air flow rate of 0.013 kg/s, which is the best mass flow rate. In addition, it has been observed that for case tow the maximum outlet air temperature and electric powers were 44.3 oC and 26.6 W, respectively. For case one, thermal and electrical efficiencies were found 34% and 10%, respectively, based on the experimental data, while for case 2, the maximum thermal and electrical efficiencies were found to be 48.9 and 9.1%, respectively

A Novel Application for Parabolic Trough Solar Collector Based on Helical Receiver Tube and Nano-Fluid with a Solar Tracking Mechanism

Saad T. Hamidi

Engineering and Technology Journal, 2020, Volume 38, Issue 5, Pages 656-668
DOI: 10.30684/etj.v38i5A.496

Novel techniques to enhance thermal performance using a helical coil receiver tube and Nano-fluid materials are presented in this paper. Two different applied techniques to enhance thermal performance are used as a new application on parabolic trough solar collector (PTSC). In the present work, PTSC has been fabricated using Dioxide Silicon SiO2 with an average particle size of 40nm by taking volume fraction of SiO2 0.1, 0.2 and 0.3%. Distilled water based Nano-fluid as a working fluid and a helical coil receiver tube were used in this paper. Varying the flow rate of Nano-fluids 100,150 and 200l/h are used, respectively. A solar tracking mechanism experimentally has been used with the PTSC. As per ASHRAE standard, the experimental results showed that at volume fraction 0.3 % and flow rate of 200 l/h, the highest increase in the energy absorbed factor FR(τα) was 14.6 % and energy removal factor FRUL was 29.4 % compared with distilled water. The changes in FR(τα) vary from 11.8% to 14.6% while in FRUL, they vary from 20.5% to 29.4% as compared with the distilled water case. The maximum efficiency was about 76.6 % as the heat loss parameter [(Ti–Ta)/GT] =0 at a volume fraction of 0.3 % and the flow rate of 200 l/h.

An Experimental Investigation on Thermal Efficiency of Flat Plate Tube Solar Collector using Nanofluid with Solar Tracking Mechanism

Saad T. Hamidi

Engineering and Technology Journal, 2019, Volume 37, Issue 11A, Pages 475-487
DOI: 10.30684/etj.37.11A.5

In the present work, flat-plate solar collector (FPSC) in terms of various parameters as well as in respect of lower (Area of FPSC, volume fraction concentration of nanofluids, and mass flow rate) has been studied in this work. The FPSC has been fabricated with 0.192 m2, Dioxide silicon SiO2 (40nm) with the volume fraction of SiO2+Distilled water (0.05, 0.075, and 0.1%) and varying of flow rate (10, 15, 20L/h). These technological devices operate under forced circulation mode of fluid under varying climate conditions. The tracking mechanism has been used in the experiment of FPSC for tracking the sun position during the daytime. As per the ASHRAE standard. The results showed that at volume fraction 0.10 % and flow rate of 20 L/h, the highest increase in the absorbed energy parameter FR(τα) was 7.3 %, and the removed energy parameter FRUL was 11.9 % compared with distilled water. The changes in absorbed energy parameter FR(τα) they vary from 4.4% to 7.3% while in removed energy parameter FRUL, the vary from 1.3% to 11.9% as compared with the distilled water case. The maximum efficiency was about 70 % as the decreased temperature parameter [(Ti–Ta)/GT] is equal to zero at a volume fraction of 0.10 % and flow rate of 20 L/h