scholarly journals Experimental Performance of a Solar Air Collector with a Perforated Back Plate in New Zealand

Energies ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1415 ◽  
Author(s):  
Yu Wang ◽  
Mikael Boulic ◽  
Robyn Phipps ◽  
Manfred Plagmann ◽  
Chris Cunningham
Keyword(s):  
Wind Speed ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Thermal Efficiency ◽  
Absorber Layer ◽  
Cover Plate ◽  
Solar Air Heater ◽  
Air Mass ◽  
Back Plate

This study investigates the thermal efficiency of a solar air heater (SAH), when it was mounted on a custom-made support frame, and was operated under different air mass flow rate. This SAH is composed of a transparent polycarbonate cover plate, a felt absorber layer, a perforated aluminium back plate and an aluminium frame. The ambient inlet air of this SAH is heated as it passes through the perforated back plate and over the felt absorber layer. The heated air is blown out through the outlet. Studies of SAHs with a similar design to this SAH were not found in the literature. The experiment was carried out at Massey University, Auckland campus, NZ (36.7° S, 174.7° E). The global horizontal solar irradiance, the ambient temperature and the wind speed were recorded using an on-site weather station. Temperature and velocity of the air at the outlet were measured using a hot wire anemometer. During the experiment, the air mass flow rate was between 0.022 ± 0.001 kg/s and 0.056 ± 0.005 kg/s. Results showed that when the SAH was operated at the airflow between 0.0054 kg/s and 0.0058 kg/s, the inlet air temperature and the wind speed (between 0 and 6.0 m/s) did not impact the temperature difference between the outlet air and the inlet air. The thermal efficiency of the SAH increased from 34 ± 5% at the airflow between 0.021 kg/s and 0.023 kg/s, to 47 ± 6% at the airflow ranging from 0.032 kg/s to 0.038 kg/s, to 71 ± 4% at the airflow of 0.056 ± 0.005 kg/s. The maximum thermal efficiency of 75% was obtained at the airflow of 0.057 kg/s. The effective efficiency of the SAH was 32 ± 5% at the airflow between 0.021 kg/s and 0.023 kg/s, 42 ± 6% at the airflow ranging from 0.032 kg/s to 0.038 kg/s, and 46 ± 11% at the airflow of 0.056 ± 0.005 kg/s.

scholarly journals Influencing Mechanisms of a Crosswind on the Thermo-Hydraulic Characteristics of a Large-Scale Air-Cooled Heat Exchanger

Energies ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 1128
Author(s):  
Yanqiang Kong ◽  
Weijia Wang ◽  
Zhitao Zuo ◽  
Lijun Yang ◽  
Xiaoze Du ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Wind Speed ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Large Scale ◽  
Air Mass ◽  
Heat Rejection ◽  
Wind Speeds ◽  
Air Cooled Heat Exchanger

For the large scale air-cooled heat exchanger of a natural draft dry cooling system (NDDCS) in power plants, its thermo-flow characteristics are basically dominated by crosswinds. Unfortunately however, the detailed mechanisms of the crosswind effects have yet to be fully uncovered. Therefore, in this research, the local flow and heat transfer performances of the cooling deltas, which are also termed as the fundamental cells of the large-scale air-cooled heat exchanger, are specifically investigated with full consideration for the cell structure and the water-side temperature distribution at various wind speeds. A 3D CFD method with a realizable k-ε turbulence model, heat exchanger model, and porous media model is developed, and the accuracy and credibility of the numerical model are experimentally validated. With the numerical simulation, the overall 3D outlet air temperature of the large-scale air-cooled heat exchanger, and the corresponding local air velocity and temperature fields of the cooling deltas are qualitatively analyzed. Furthermore, the air-mass flow rate and heat rejection are also quantitatively studied at both the global and local views. The results depict that with an increase in the wind speed, the air mass flow rate and heat rejection will increase greatly for the frontal deltas; however, they will drop dramatically for the middle-front deltas. As for the middle- as well as the middle-rear deltas, the thermo-flow performances vary markedly at various wind speeds, which behave in the most deteriorated manner at a wind speed of 12 m/s. The rear deltas show the best thermo-flow performances at a wind speed of 12 m/s, but the worst at 16 m/s. A detailed analysis of the variable fields for each cooling delta may contribute to the performance improvement of the large-scale air-cooled heat exchanger of NDDCS.

scholarly journals Experimental Study of the Slit Spacing and Bed Height on the Thermal Performance of Slit-Glazed Solar Air Heater

2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
Seyyed Mahdi Taheri Mousavi ◽  
Fuat Egelioglu
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Ambient Air ◽  
Solar Air Heater ◽  
Outlet Temperature ◽  
Flow Rates ◽  
Air Mass ◽  
Bed Height ◽  
Mass Flow Rates

The thermal performances of three slit-glazed solar air heaters (SGSAHs) were investigated experimentally. Three SGSAHs with different bed heights (7 cm, 5 cm, and 3 cm) were fabricated with multiple glass panes used for glazing. The length, width, and thickness of each pane were 154 cm, 6 cm, and 0.4 cm, respectively. Ambient air was continuously withdrawn through the gaps between the glass panes by fans. The experiments were conducted for four different gap distances between the glass panes (0.5 mm, 1 mm, 2 mm, and 3 mm) and the air mass flow rate was varied between 0.014 kg/s and 0.057 kg/s. The effects of air mass flux on the outlet temperature and thermal efficiency were studied. For the SGSAH with bed height of 7 cm and glass pane gap distance of 0.5 mm, the highest efficiency was obtained as 82% at a mass flow rate of 0.057 kg/s and the air temperature difference between the inlet and the outlet (∆T) was maximum (27°C) when the mass flow rate was least. The results demonstrate that for lower mass flow rates and larger gaps, the performance of SGSAH with a bed height of 3 cm was better compared to that of others. However, for higher mass flow rates, the SGSAH with 7 cm bed height performed better.

scholarly journals Experimental Study of Artificial Solar Air Heater Using Trapezoidal Wave Plate

2019 ◽  
Vol 4 (2) ◽  
pp. 135-148
Author(s):  
Lohdy Diana ◽  
Arrad Ghani Safitra ◽  
Muhammad Syarifuddin Firmansyah ◽  
Mishbaakhus Prana Zinedine
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Airflow Rate ◽  
Halogen Lamp ◽  
Solar Air Heater ◽  
Air Mass ◽  
Wave Plate ◽  
Air Heater ◽  
Air Heating

A solar air heater is needed for the drying process, especially in Indonesia.  It means the researches to produce a solar air heater that had high performance is necessary. This research analyses the performance of solar air heater using trapezoidal absorber plate with variation of folded angle 83˚, 85˚, and 87˚. The research carry out artificial experimentally using halogen lamp as a solar simulator. The working principle of solar air heating begins with an induction fan sucking air to enter through the honeycomb then flowing into the air heating duct. The process of heat transfer occurs in a halogen heat lamp passed by the transparent glass and then absorbed by the absorbent plate. This heat will heat the air flowing in the air heating pipe to be transmitted into the drying cupboard. The experiment used several variations of the mass airflow rate 0.022 until 0.051 kg/s and intensity 850, 900, dan 950 W/m2. Temperature measurement is carried out by installing a thermocouple at several points that have been determined. The best performance produced by the wave plate-shaped trapezoidal wave heaters 83˚ when I = 950 W/m2 air mass flow rate 0.022 kg/s with the temperature of the absorbent plate 87 ˚C, the temperature of the exit air 43.2 ˚C, the difference in the rise in air temperature 15.2 ˚C, and when I = 950 W/m2 air mass flow rate 0.051 kg/s the useful heat generated by the air heater 527 Watt, and thermal efficiency 96.8%.

scholarly journals Influence of active water stream, irradiance, ambient temperature and wind speed on the efficiency of Fresnel lens based two stage PVT system

2021 ◽  
pp. 193-193
Author(s):  
Arvind Singhy ◽  
Robin Thakur ◽  
Raj Kumar ◽  
Sushil Kumar ◽  
Sanjeev Kumar ◽  
...  
Keyword(s):  
Wind Speed ◽  
Ambient Temperature ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Thermal Efficiency ◽  
Fresnel Lens ◽  
Water Stream ◽  
Electrical Efficiency ◽  
Water Mass Flow Rate

Influence of wind speed, mass flow rate of water, irradiance and ambient temperature on concentrated Photovoltaic thermal module equipped with linear FL as Primary Optic Element and Convex Lens as Secondary Optic Element have been investigated in this study. Influence of these parameters on module performance in terms of thermal efficiency and electrical efficiency are also examined during investigation. The thermal efficiency and electrical efficiency without consideration of parameters was found to be 14.3% and 51.2 % respectively. With consideration of above mentioned four parameters, the results reveal that electrical efficiency of 17.2% and thermal efficiency of 55.3% can be achieved for designed setup. Thus, there is 20% and 8% increase in electrical efficiency and thermal efficiency respectively. The electrical efficiency increases with increase in fluid flow rate, wind speed and irradiance. Electrical efficiency decreases with increase in ambient temperature. The thermal efficiency increases with increment in water mass flow rate, irradiance and ambient temperature. However, with increase in wind speed, the thermal efficiency decreases.

Investigation of the Thermal Performances of Flat, Finned, and v-Corrugated Plate Solar Air Heaters

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
A. E. Kabeel ◽  
A. Khalil ◽  
S. M. Shalaby ◽  
M. E. Zayed
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Thermal Efficiency ◽  
Convective Heat Transfer Coefficient ◽  
Operating Conditions ◽  
Experimental Results ◽  
Solar Air Heater ◽  
Outlet Temperature ◽  
Air Heater

In this research, the thermal performances of flat, finned, and v-corrugated plate solar air heaters were investigated experimentally. A solar air heater with single glass cover, single pass was designed and tested under prevailing weather conditions of Tanta city (30°43′ N, 31° E), Egypt. The solar air heater was designed to be easy to replace the absorber plate from one to another one. Comparisons between the temperature difference of air across the heater and thermal efficiencies of the flat, finned, and v-corrugated plate solar air heaters were presented. The effect of change in the mass flow rate of air on the outlet air temperature and the thermal efficiency of the heater were also studied when the mass flow rates were 0.062, 0.028, and 0.009 kg/s. The experimental results showed that the maximum value of outlet temperature of the v-corrugated plate solar air heater was 5 and 3.5 °C more than that of flat and finned plates when the mass flow rate was 0.062 kg/s, respectively. And, it increased to be 8 and 5.5 C when the mass flow rate was 0.009 kg/s. It is also indicated that the thermal efficiency of the v-corrugated solar air heater is 8–14.5% and 6–10.5% higher than that of the flat and finned plate heaters, respectively, when the mass flow rate was 0.062 kg/s under the considered configurations and operating conditions. The experimental results also indicated that the convective heat transfer coefficient of the v-corrugated heater reached up to 1.64 and 1.36 times than that of the flat and finned heaters, respectively, when the flow rate was 0.062 kg/s.

Double Duct Packed Bed Solar Air Heater Under Combined Single and Recyclic Double Air Pass

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Satyender Singh ◽  
Prashant Dhiman
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Packed Bed ◽  
Wire Mesh ◽  
Solar Air Heater ◽  
Double Pass ◽  
Air Mass ◽  
Air Heater ◽  
Recycle Ratio

The present work intended to investigate thermal and thermohydraulic efficiencies of two different models of recyclic double pass packed bed solar air heaters experimentally. Model-I consists of single air pass through two glass covers as well as double air pass caused due to recycle of the air exiting from the packed bed duct formed between the absorber plate and the glass cover through another duct integrated between the absorber and back plates to inlet of the packed bed duct. On the other hand, model-II consists of only double air pass originated due to recycle operation constituted between the similar solar air heater elements as that of model-I. Twelve numbers of wire mesh screens to form 95% bed porosity were used. Both solar air heater models were tested under the range of packed bed Reynolds number from 300 to 1500 for air mass flow rate and recycle ratio of 0.01 kg/s to 0.025 kg/s and 0.3 to 1.8, respectively. Results revealed that thermal performance of model-I is found to be 15% higher than that of model-II. The optimum value of the recycle ratio for model-I and model-II are obtained as 0.9 and 1.2, respectively, at a mass flow rate of 0.025 kg/s that yields the best thermohydraulic efficiency of 77% and 67%, respectively. Moreover, optimum solution for recycle ratio and air mass flow rate during off sun shine hours are also obtained and presented in the current work.

scholarly journals Transient computational fluid dynamics investigations on thermal performance of solar air heater with hollow vertical fins

2018 ◽  
Vol 22 (6 Part A) ◽  
pp. 2389-2399 ◽  
Author(s):  
Duraisamy Jagadeesh ◽  
Ramasamy Venkatachalam ◽  
Gurusamy Nallakumarasamy
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Thermal Performance ◽  
Experimental Work ◽  
Thermal Efficiency ◽  
Solar Air Heater ◽  
Outlet Temperature ◽  
Absorber Plate ◽  
Air Dryer

Evaluation of experimental thermal performance of a single pass solar air dryer is compared with a transient CFD studies is performed. Vertical hollow plates are placed below the absorber plate and compared against the flat solar absorber plate for its performance improvement. Effect of mass-flow rate, the outlet temperature of air is computationally analyzed in comparison with the experimental work, transient boundary conditions for CFD like ambient temperature, solar insolation are taken from the experimental work, and computational results are in good agreement of with experimental results with maximum error percentage of 10%. Thermal efficiency was increased with increase in mass-flow area for without fin configuration, for a specific mass-flow rate thermal efficiency had a good improvement with fin configuration than the without fin configuration.

scholarly journals Determination of a Methodology to Derive Correlations Between Window Opening Mass Flow Rate and Wind Conditions Based on CFD Results

Energies ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1600 ◽  
Author(s):  
Panagiotis Stamatopoulos ◽  
Panagiotis Drosatos ◽  
Nikos Nikolopoulos ◽  
Dimitrios Rakopoulos
Keyword(s):  
Wind Speed ◽  
Numerical Simulations ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Empirical Equation ◽  
Ventilation Rate ◽  
Cfd Simulations ◽  
Air Mass ◽  
Adjacent Room

This paper presents a methodology for the development of an empirical equation which can provide the air mass flow rate imposed by single-sided wind-driven ventilation of a room, as a function of external wind speed and direction, using the results from Computational Fluid Dynamics (CFD) simulations. The proposed methodology is useful for a wide spectrum of applications, in which no access to experimental data or conduction of several CFD runs is possible, deriving a simple expression of natural ventilation rate, which can be further used for energy analysis of complicated building geometries in 0-D models or in object-oriented software codes. The developed computational model simulates a building, which belongs to Rheinisch-Westfälische Technische Hochschule (RWTH, Aachen University, Aachen, Germany) and its surrounding environment. A tilted window represents the opening that allows the ventilation of the adjacent room with fresh air. The derived data from the CFD simulations for the air mass flow were fitted with a Gaussian function in order to achieve the development of an empirical equation. The numerical simulations have been conducted using the Ansys Fluent v15.0® software package. In this work, the k-w Shear Stress Transport (SST) model was implemented for the simulation of turbulence, while the Boussinesq approximation was used for the simulation of the buoyancy forces. The coefficient of determination R2 of the curve is in the range of 0.84–0.95, depending on the wind speed. This function can provide the mass flow rate through the open window of the investigated building and subsequently the ventilation rate of the adjacent room in air speed range from 2.5 m/s to 16 m/s without the necessity of further numerical simulations.

Numerical analysis of a solar air heater with jet impingement - comparison of performance between jet designs

2021 ◽  
pp. 1-24
Author(s):  
Supreme Das ◽  
Agnimitra Biswas ◽  
Biplab Das
Keyword(s):  
Heat Transfer ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Thermal Efficiency ◽  
Flow Behavior ◽  
Jet Impingement ◽  
Solar Air Heater ◽  
Circular Jets ◽  
Improved Performance

Abstract One of the ways to improve the performance of solar air heaters (SAH) is to use jet impingement on the absorber plate to cause turbulence mixing of air in contact with the plate and thereby augment the heat transfer coefficient. The objective of this work is to compare the thermohydraulic performance of a SAH with jet impingement through conical protruding jets and circular jets using finite element method based COMSOL Multi-physics software. The simulation studies were conducted for solar radiation in the range 500 – 1000 W/m2 and mass flow rate in the range 0.01 – 0.028 kg/s. The flow physics of the jet impingement process is investigated to understand the heat transfer and fluid flow behavior of the SAH with the chosen jet designs thereby obtain their performance insights. The outlet hot air temperature from the heater and its thermal efficiency are compared for different mass flow rates and solar radiations. Also the temperature distributions in the jet plate with the jet configurations are captured and their heat transfer characteristics compared to understand the thermo-fluidic behavior of the SAH. The results demonstrate improved performance of the novel conical protruded jet design that enhances the thermal efficiency up to 78.52%, which is an increase of 13.53% compared to the circular jet design. More elongated streamlines and higher turbulent kinetic energy with increased mass flow rate leading to a wide jet affected area inside the duct are the main reasons of its improved performance.

scholarly journals Performances of packed bed double pass solar air heater with different inclinations and transverse wire mesh with different intervals

2016 ◽  
Vol 20 (1) ◽  
pp. 175-183 ◽  
Author(s):  
Gnanadurai Sugantharaj ◽  
Kumar Vijay ◽  
Kalidasa Kulundaivel
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Thermal Efficiency ◽  
Packed Bed ◽  
Wire Mesh ◽  
Solar Air Heater ◽  
Double Pass ◽  
Air Heater ◽  
Collector Efficiency

Solar air heating is a technology in which the solar energy from the sun is captured by an absorbing medium and used to heat the air flowing through the heater. In this study, thermal performance of a double pass solar air heater has been investigated experimentally at different conditions. The experiments were conducted with different inclinations of the collector, with and without wire mesh vertically fixed at the second pass in transverse direction and with different mass flow rates. The effect of air mass flow rate, wire mesh pitch and collector inclination on temperature rise and thermal efficiency have been studied. Results show that efficiency increases with mass flow rate. For the same mass flow rate, the thermal efficiency increases with the decrease in the wire mesh pitch. The maximum daily average efficiency of air heater was 79.8% at 0.025 kg/s mass flow rate, 10 cm wire mesh gap and 9? collector inclination facing south. The highest collector efficiency was observed in solar air heaters with 10 cm wire mesh gap.

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