Preliminary Results of Testing a Solar Air Heater Equipped with Turbulators

2017 ◽  
Author(s):  
Miroslaw Zukowski ◽  
Grzegorz Woroniak
Keyword(s):  
Solar Radiation ◽  
Thermal Performance ◽  
Meteorological Data ◽  
Air Flow ◽  
Solar Air Heater ◽  
Outlet Temperature ◽  
Time Intervals ◽  
Measurement Results ◽  
New Type ◽  
Flow Through

The paper presents the thermal performance of a newly designed device for preheating ventilation air. This new type of a solar air collector is equipped with turbulators to increase heat exchange and eventually to obtain more energy from the Sun. Support elements of this type have not yet been implemented in such heat exchangers. The panel has the following dimensions: width – 0.97 m, length – 1.9 m, thickness – 0.1 m, the area where solar radiation enters the collector – 1.49 m2. Air flow through the exchanger is forced by two radial high flow fans, typically used to cool down servers. The test stand beside the collectors is equipped with an inlet and outlet temperature data recorder and an anemometer to control the air flow rate through the collector. Meteorological data such as solar radiation, wind speed and ambient temperature is obtained from a weather station. The parameters of the working installation have been analysed through the monitoring of measurement variables collected on one-minute time intervals from April to September 2016. The measurement results have been used to determine the thermal performance of the air solar collector of this type. The results of the energy analysis have shown the validity of such an installation.

The Research of Energy Conversion and Heat Transfer in the Ceramic Foams of Solar Energy Converter

2011 ◽  
Author(s):  
Yangbo Deng ◽  
Fengmin Su ◽  
Chunji Yan
Keyword(s):  
Heat Transfer ◽  
Numerical Model ◽  
Solar Radiation ◽  
Solar Energy ◽  
Numerical Models ◽  
Air Flow ◽  
Energy Converter ◽  
Ceramic Foams ◽  
Numerical Studies ◽  
Flow Through

The solar energy converter in Concentrated Solar Power (CSP) system, applies the solid frame structure of the ceramic foams to receive the concentrated solar radiation, convert it into thermal energy, and heat the air flow through the ceramic foams by convection heat transfer. In this paper, first, the pressure drops in the studied ceramic foams were measured under all kinds of flow condition. Based on the experimental results, an empirical numerical model was built for the air flow through ceramic foams. Second, a 3-D numerical model was built, for the receiving and conversion of the solar energy in the ceramic foams of the solar energy converter. Third, applying two aforementioned numerical models, the numerical studies of the thermal performance were carried out, for the solar energy converter filled with the ceramic foams, and results show that the structure parameters of the ceramic foams, the effective reflective area and the solar radiation intensity of the solar concentrator, have direct impacts on the absorptivity and conversion efficiency of the solar energy in the solar energy converter. And the results of the numerical studies are found to be in reasonable agreement with the experimental measurements. This paper will provide a reference for the design and manufacture of the solar energy converter with the ceramic foams.

scholarly journals Thermal Evaluation of a Double-Pass Unglazed Solar Air Heater with Perforated Plate and Wire Mesh Layers

2020 ◽  
Vol 12 (9) ◽  
pp. 3619
Author(s):  
Afaq Jasim Mahmood
Keyword(s):  
Flow Rate ◽  
Thermal Efficiency ◽  
Air Flow ◽  
Wire Mesh ◽  
Inlet Temperature ◽  
Solar Air Heater ◽  
Outlet Temperature ◽  
Air Flow Rate ◽  
Double Pass ◽  
Air Heater

In this study, an experimental outdoor investigation of the thermal efficiency and outlet air temperature was conducted on an unglazed, double-pass, solar air heater with a perforated absorber plate and packing wire mesh layers as a supplemental absorbent area. This was done to observe their effects on the thermal performance of the solar air heater. The double-pass collector was constructed with a bed height of 0.05 m, and a collection area of 1.5 m2. The height of the upper channel was fixed at 0.015 m to improve the thermal efficiency, and the outlet temperature at air flow rates between 0.003 and 0.018 kg/s. The collector was mounted with a slope of 42° facing south, to maximize the intensity of solar irradiance during winter. The effects of the air flow rate, ambient temperature, inlet temperature, outlet temperature, and solar intensity were experimentally investigated. The results showed that thermal efficiency could be improved by increasing the air flow rate, where the highest thermal efficiency achieved was 86% at 0.018 kg/s. However, the temperature difference was increased to a maximum value of 38.6 °C, when the air flow rate was decreased to 0.003 kg/s. Furthermore, the results demonstrated a significant improvement in the thermal efficiency and outlet temperature; and when compared with previous research, the experimental results and the predictions for the outlet temperature using the theoretical model agreed.

scholarly journals Experimental Investigation of the Thermal Performance of a Solar Air Heater

2021 ◽  
Vol 9 (2) ◽  
Author(s):  
Abdulghani M. Ramadan ◽  
Khairi Muftah ◽  
Abdul-Rahman Al-Naaji ◽  
Abdul-Baset Al-Soul ◽  
Akram A. Essnid ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Solar Radiation ◽  
Mass Flow ◽  
Thermal Performance ◽  
Operating Conditions ◽  
Space Heating ◽  
Solar Air Heater ◽  
Air Mass ◽  
Incident Solar Radiation ◽  
Air Heater

Solar air heaters are widely used in many low temperature applications such as space heating, crops drying, desalination..etc. It collects solar radiant energy and transforms it into heat through a fluid (air) flowing inside the system. The outside cold air is heated through the system and delivered to the required application. It is simple, economic and clean. In this study, an experimental investigation is carried out using a test-rig installed at the laboratories facility for Center of Solar Energy Research and Studies (CSERS) in Tajoura-Libya equipped with all necessary measuring instruments and devices. The aim of this study is to investigate the effect of process air mass flow rate on the thermal performance of a solar air heater working at different operating conditions under the prevailing conditions of Tajoura-Libya. Experiments were conducted on specified days in August 2019, October 2019 and January, 2020.Results show that there is a noticeable increase in the air temperatures of the solar air heater as incident solar radiation values increase during the day time, especially at afternoon. The maximum average outlet air temperature measured reaches 60 oC which is suitable for space heating and crops drying applications. Useful heat energy collected is directly proportional to the incident solar radiation. Increasing air mass flow rates leads to a corresponding decrease in the temperature at different locations in the solar air heater. Furthermore, the average thermal efficiency values of the solar air heater range from 35% to 65%. Average overall heat loss coefficient values tend to decrease with the day time. Finally, the present study results coincide with literature and show a good agreement.

Heat Exchange Effectiveness and Pressure Drop for Air Flow Through Perforated Plates With and Without Crosswind

1994 ◽  
Vol 116 (2) ◽  
pp. 391-399 ◽  
Author(s):  
C. F. Kutscher
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Pressure Drop ◽  
Air Flow ◽  
Ambient Air ◽  
Perforated Plates ◽  
Wind Speeds ◽  
New Type ◽  
Flow Through ◽  
Heat Exchange Effectiveness

Low-porosity perforated plates are being used as absorbers for heating ambient air in a new type of unglazed solar collector. This paper investigates the convective heat transfer effectiveness for low-speed air flow through thin, isothermal perforated plates with and without a crosswind on the upstream face. The objective of this work is to provide information that will allow designers to optimize hole size and spacing. In order to obtain performance data, a wind tunnel and small lamp array were designed and built. Experimental data were taken for a range of plate porosities from 0.1 to 5 percent, hole Reynolds numbers from 100 to 2000, and wind speeds from 0 to 4 m/s. Correlations were developed for heat exchange effectiveness and also for pressure drop. Infrared thermography was used to visualize the heat transfer taking place at the surface.

Flow Control and Unsteady-State Analysis on Thermal Performance of Solar Air Collectors

2006 ◽  
Vol 128 (3) ◽  
pp. 354-359 ◽  
Author(s):  
Sadasuke Ito ◽  
Minoru Kashima ◽  
Naokatsu Miura
Keyword(s):  
Control System ◽  
Solar Radiation ◽  
Flow Control ◽  
Flow Rate ◽  
Thermal Performance ◽  
Space Heating ◽  
Outlet Temperature ◽  
Unsteady State ◽  
Collector Efficiency ◽  
Unsteady State Analysis

Promotion of the use of renewable energy, such as solar heat, for space heating and drying crops and wood is desired to prevent global warming. High-temperature collection of heat by air collectors producing as much as 50°C in winter for space heating and about 80°C in summer for exchanging heat to circulating water for hot water supply would be appropriate applications. In this study, first, a flow control system for constant outlet temperature was installed in a hot air supply system to examine the feasibility of the control system. After experiments, it was found that the control system could function satisfactory. Second, an unsteady-state analysis was made to predict the thermal performance of a flat-plate collector under a given condition of variable flow rate. The analytical model became simple by the assumptions that the heat capacity of the air in the collector and heat conduction in the flow direction through the air and the materials of the collector could be neglected. The maximum differences in outlet temperature and collector efficiency for constant flow rate between the analysis and the experiment were 1.8°C and 6% of the collector efficiency, respectively, except in the beginning of experiments. The biggest difference in the collector efficiency was 30% at 3:00 P.M., which occurred at the end of one of the experiments. The analytical results generally agreed well with the experimental results even when the flow rate and solar radiation changed greatly as time went on. Transient effects are important to predict outlet temperature for variable solar radiation intensity, wind speed, and flow rate.

Effect of Inlet Location on Ventilation Flow Through a Room Fitted With Solar Chimney

2018 ◽  
Author(s):  
Kashif Nazir ◽  
B. P. Huynh
Keyword(s):  
Solar Radiation ◽  
Flow Pattern ◽  
Natural Ventilation ◽  
Air Flow ◽  
Ventilation Rate ◽  
Navier Stokes ◽  
Computational Domain ◽  
Solar Chimney ◽  
Flow Through ◽  
Inlet Opening

Solar chimney (thermal chimney) is a device which absorbs solar radiation to heat the air. The heated air, becoming buoyant, rises through the chimney’s passage and induces further air currents. When fitted to a building, solar chimney can thus induce fresh outside air to flow through the building for ventilation. Because only natural means (solar radiation here) are involved to cause the air flow, solar chimney is considered a natural-ventilation device. This work investigates computationally natural ventilation induced by a roof-mounted solar chimney through a real-sized 3-dimensional room, using a commercial CFD (Computational Fluid Dynamics) software package which employs the Finite Volume Method. Chien’s turbulence model of low-Reynolds-number K-ε is used in a Reynolds-Averaged Navier-Stokes (RANS) formulation. Computational domain that includes regions outside the room’s inlet opening and chimney’s exit allows for employing realistic boundary conditions for the computational model. Ventilation rate and air-flow pattern through the room are considered in terms of the location of the room’s inlet opening. It is found that while ventilation flow-rate through the room is higher with the room-inlet opening being located high on the wall opposite to the chimney’s entrance, a room-inlet opening being located near the ground results in better flow pattern with more flow through the living area in the lower part of the room.

scholarly journals Experimental Study of Thermal Performance of One-Ended Evacuated Tubes for Producing Hot Air

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Ashish Kumar ◽  
Sanjeev Kumar ◽  
Utkarsh Nagar ◽  
Avadhesh Yadav
Keyword(s):  
Thermal Performance ◽  
Temperature Difference ◽  
Air Flow ◽  
Climatic Conditions ◽  
Working Fluid ◽  
Outlet Temperature ◽  
Flow Rates ◽  
Solar Air Collector ◽  
Evacuated Tubes ◽  
Evacuated Tube

The thermal performance of an evacuated tube solar air collector is experimentally investigated at different air flow rates. Air is used as a working fluid in experimental setup and tested in Indian climatic conditions. The evacuated tube solar air collector consists of fifteen evacuated tubes and manifold channel. The manifold channel consists of a hollow pipe (square pipe) in centre through which air flows. The temperature difference and efficiency are studied with different air flow rates. The reflectors are used to enhance the performance of evacuated tubes solar air collector. It is observed that in case of reflector evacuated tube solar air collector gives higher outlet temperature and temperature difference and has better thermal performance as compared to the case without reflector. The maximum outlet temperature and temperature difference of air are found to be 97.4°C and 74.4°C at a flow rate of 6.70 kg/hr.

Soft magnetorheological elastomers as new actuators for valves

2012 ◽  
Vol 23 (9) ◽  
pp. 989-994 ◽  
Author(s):  
Holger Böse ◽  
Raman Rabindranath ◽  
Johannes Ehrlich
Keyword(s):  
Magnetic Field ◽  
Magnetic Particles ◽  
Air Flow ◽  
Inhomogeneous Magnetic Field ◽  
Magnetorheological Elastomer ◽  
Magnetorheological Elastomers ◽  
Type Device ◽  
New Type ◽  
Flow Through ◽  
The Magnetic Field

The actuation behavior of soft silicone-based magnetorheological elastomers in magnetic fields of variable strength was investigated. An inhomogeneous magnetic field gives rise to a reversible actuation effect, which is the result of the competition between magnetic and elastic forces in the material. Magnetorheological elastomers are capable of performing more pronounced deformations than known rigid actuator materials. In this article, the actuation behavior of magnetorheological elastomer ring-shaped bodies in a valve-type device for the control of an air flow is demonstrated. For this purpose, magnetorheological elastomer rings with different Shore hardness were prepared and used in the valve. In addition to the common isotropic magnetorheological elastomer samples, rings with an anisotropic arrangement of the magnetic particles were also prepared. The actuation of these anisotropic magnetorheological elastomers was compared with that of the isotropic samples. Based on simulations, the inhomogeneity of the magnetic field at the magnetorheological elastomer material which is required for the actuation could be strongly affected by the shape in the design of the magnetic yoke. In this study, the closing characteristics of the valve with different yoke shapes and magnetorheological elastomer materials were evaluated by measuring the dependence of the air flow rate on the magnetic field strength. It is demonstrated that the air flow through the valve can be controlled by the current in the field-generating coil, which yields the base for a new type of magnetic valve.

A Repetitive Day Method for Predicting the Long-Term Thermal Performance of Passive Solar Buildings

1990 ◽  
Vol 112 (1) ◽  
pp. 34-42 ◽  
Author(s):  
D. Feuermann
Keyword(s):  
Solar Radiation ◽  
Ambient Temperature ◽  
Thermal Performance ◽  
Meteorological Data ◽  
Climatic Data ◽  
Temperature Model ◽  
Governing Equations ◽  
Model Calculations ◽  
Passive Solar

The long-term thermal performance of passively-heated solar buildings is predicted by a single repetitive meteorological day which contains judiciously chosen solar radiation and ambient temperature functions. These are used as the driving functions of the governing equations that describe the passive solar building under study. The solar radiation and ambient temperature functions are chosen such that they include, both qualitatively and quantitatively, the essential radiation and temperature statistics of the climate in which the building is to be located. The relevant statistics are determined from hourly meteorological data. When hourly meteorological data are not available for a given location, the solar radiation and ambient temperature functions can be constructed from the knowledge of only two climatic data, namely, the monthly average horizontal radiation and the ambient temperature. Model calculations compare favorably with experimental data from Los Alamos solar test cells and with computer simulations.

scholarly journals Investigation on The Thermal Performance of Evacuated Glass-Thermal Absorber Tube Collector (EGATC) for Air Heating Application

2021 ◽  
Vol 79 (2) ◽  
pp. 48-64
Author(s):  
Zairul Azrul Zakaria ◽  
Zafri Azran Abdul Majid ◽  
Muhammad Amin Harun ◽  
Ahmad Faris Ismail ◽  
Sany Izan Ihsan ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Thermal Performance ◽  
Glass Tube ◽  
Heating System ◽  
Outlet Temperature ◽  
Water Heating ◽  
Diffuse Solar Radiation ◽  
Air Heating ◽  
Outdoor Experiment ◽  
Flat Plate Collector

Existing design of Heat-Pipe Evacuated Tube Collector (HP ETC) for solar water heating require storage tank and additional heat exchanger required for air heating application which leads to the extra spacing and costing requirement. HP ETC have better thermal performance to produce high outlet temperature than flat plate collector (FPC), especially during diffuse solar radiation. But HP ETC normally focusing on water heating system. Furthermore, HP ETC and FPC installation need to be positioned either to south or north facing to ensure the solar thermal collector absorbs more solar radiation. Meanwhile, HP ETC need to be tilt at the correct angle to maximize the performance of the system. These could lead to design limitation. The aim of this research is to develop the new design of Evacuated Glass-Thermal Absorber Tube Collector namely EGATC for drying application. It was developed from conventional HP ETC evacuated glass tube. In this study comparison result of EGATC and HP ETC performance were evaluated. The three days outdoor experiment proves that the performance of EGATC was better than HP ETC in air heating application which is provide higher outlet temperature. Based on the result, EGATC (Day 1: 50.9 oC, Day 2: 53.9 oC, Day 3: 49.2 oC) performed better with slightly higher temperature at outlet temperature compare with HP ETC (Day 1: 46.7 oC, Day 2: 50.3 oC, Day 3: 46.9 oC). It is concluded that EGATC have better performance in term of temperature different and outlet temperature as compared to HP ETC. EGATC (Day 1: 53.6%, Day 2: 50.6%, Day 3: 49.8%) also have greater efficiency in term of heat storage capability as compared to HP ETC (Day 1: 42.7%, Day 2: 41.6%, Day 3: 41.1%). Regarding energy buffer storage, EGATC have better energy storage compared to HP ETC at sudden weather change such as diffuse solar radiation during clouds. The outlet temperature of EGATC (42.3 oC) was remained slightly higher compared to HP ETC (39.9 oC) at the beginning. The outlet temperature gradually drops slower during discharging period until the end of the experiment for 15 minutes towards outlet temperature 41.1ºC and 37.2ºC for both EGATC and HP ETC with temperature difference 1.2ºC and 2.7ºC respectively.

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