An energy and exergy study of a solar thermal air collector (original) (raw)
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Energy, Exergy and Efficiency Analysis of a Flat Plate Solar Collector used as Air Heater
Sains Malaysiana
Air heating by solar collectors is renewable technology providing hot air for different purposes. The present research emphasizes on analysis of energy, exergy and efficiency of a flat plate solar air heater. The analysis model was tested on five different air mass flow rates of 0.5 (Natural), 1.31, 2.11, 2.72 and 3.03 kgs-1 under three different tilt angles of 25, 35 (Recommended) and 50 o. The data was replicated three times making a total of 45 treatments. A two factorial completely randomized design was used to find if there is any significant difference among the treatments. The results showed that the solar collector gave better performance at air mass flow of 3.03 kgs-1 under tilt of 35 o. At maximum air mass flow rate of 3.03 kgs-1 and optimum tilt angle of 35 o the maximum energetic efficiency of 51%, while minimum exergetic efficiency of 24% and maximum overall efficiency of 71% were recorded. It was concluded that to get maximum thermal efficiencies of 71% from flat plate solar collector used as an air heater must be operated at high air mass flow rates of 3.03 kgs-1 under 35 o tilt angle at Peshawar, Pakistan.
Energetic and exergetic aspects of solar air heating (solar collector) systems
Renewable and Sustainable Energy Reviews, 2013
a b s t r a c t Solar air heating (solar collector) is a renewable heating technology and provides heat using solar energy. With fuel costs and other factors, solar air heaters (SAHs) are getting more attention. The energetic and exergetic performance of SAHs is influenced by a number of factors. The present study reviews the previously conducted studies and applications in terms of design, performance assessment, heat transfer enhancement techniques, experimental and numerical works, thermal heat storage, effectiveness compassion and recent advances. It may be concluded that energy analysis method has been used in a number of studies while exergy analysis method has been applied to the relatively low numbers of systems. Energy efficiencies of solar air collectors reviewed varied from 47% and 89%. It is expected that this comprehensive study will be very beneficial to everyone involved or interested in the energetic and exergetic design, simulation, analysis, test and performance assessment of SAHs.
Exergy analysis of the air solar collector based on experimental data
An experimental study of solar collectors with a collecting area of 4.2 m 2 and a variable flow rate of 0.02~0.06 kg/s was developed. During the operation of the solar collector, entropy is generated due to the frictional forces occurring at the flow of the working fluid through the solar heater serpentine as well as due to the heating processes of the working fluid of the solar collector. The generated irreversibility contributes to the decrease of the exergy efficiency and produces unwanted effects upon the ambient environment. The aim of this paper is to establish the optimum flow rate of the working fluid for the collector's area established by construction. In this way, the exergy efficiency is improved and the negative impact on the ambient environment is minimized. For a solar collector with an area of 4.2 m 2 , the optimum flow rate of the working fluid is 0.04 kg/s. The exergy transferred by the collector to the working fluid is 6.41% based on the exergy received from the Sun in an average summer day, for a flow rate of 0.04 kg/s.
Renewable Energy, 2013
The aim of this study is to provide a remedy for the low thermo-physical properties of air which is used as different absorber surface of air heater. This paper presents an experimental investigation on the absorber surface of the collector whose shape and arrangement were made up to provide better heat transfer surfaces. In the study an experimental performance and exergy analysis of five types of air heating solar collectors: corrugated trapeze, reverse corrugated, reverse trapeze, and a base flat-plate collector are presented. The results of the experiments were evaluated at the same time of the days with the same radiation. The efficiencies were determined for the collectors and comparisons were made among them. The present data showed that heat transfer coefficient and pressure drop increase with shape of absorbers surface.
PERFORMANCE STUDY OF A SOLAR AIR HEATER
In the present work an attempt has been made to experimentally investigate the performance of a flat plate solar air heater. Experiments were performed to find the energy and exergy efficiency at different mass flow rate of air. It is observed that for a 16% increase in mass flow rate of air, energy efficiency increases by 20%, whereas exergy efficiency increases by 36%.
Experimental investigation of three different solar air heaters: Energy and exergy analyses
The present study aims to compare three different types of designed flat-plate solar air heaters, two having fins (Type II and Type III) and the other without fins (Type I), one of the heater with a fin had single glass cover (Type III) and the others had double glass covers (Type I and Type II). The energy and exergy output rates of the solar air heaters were evaluated for various air flow rates (25, 50 and 100 m 3 /m 2 h), tilt angle (0°, 15°and 30°) and temperature conditions versus time. Based on the energy and exergy output rates, heater with double glass covers and fins (Type II) is more effective and the difference between the input and output air temperature is higher than of the others. Besides, it is found that the circulation time of air inside the heater played a role more important than of the number of transparent sheet. Lower air flow rates should be preferred in the applications of which temperature differences is more important.
Abstract – The present research study includes thermal energy performance analysis of a flat plate solar collector, in order to cover a sensitivity analysis about effective variables contributed to performance increasing approach. To obtain that, energy and momentum governing equations on a flat plate thermal collector were developed to achieve air output temperature and velocity profiles both in model and experiment. The model theory is validated with experiments by a set of flat plate thermal collectors, those located in (35 ◦ 44 35 N, 50 ◦ 57 25 E) coordinates and then were applied to carry out experimental activities. Quantitative results depicted that the mean difference between predicted and measured output air temperature in natural and forced convection scenarii is 1.47 ◦ C (3.5%) and 0.9 ◦ C (1.5%), respectively; however earlier research works and studies mentioned in literature, include error percentages in the range of 4–10%. Another quantification about, the average error percentages of estimated amounts of output air velocity profile values in natural and forced convection scenarii is 9% and 4%, respectively. This issue realizes the developed model in forced convection scenario more accurate than natural convection scenario.
Review on Exergy and Energy Analysis of Solar Air Heater
International Journal of Power Electronics and Drive System (IJPEDS), 2018
Solar air heater (SAH), which is the most essential component of solar drying systems, receive solar energy and convert it into thermal energy. This review presents descriptions and previous works conducted on performances analysis of SAHs. Exergoenviroeconomic, exergoenvironmental, environmental, and exergy analyses are also presented. In addition, results on the performances of SAHs are summarized. The exergy and energy efficiencies of SAHs at laboratorium testing range from 8% to 61% and from 30% to 79%, respectively.
STUDIES ON THE THERMAL PERFORMANCE OF A SOLAR AIR HEATER
In the present work, an attempt has been made to investigate the thermal performance of a flat plate solar air heater. Analytical Thermal model for the flat plate solar air heater is presented. Experimental observations were made in Indian (25º N, 81º E) climatic conditions. Maximum 10 % variation is found between the theoretical and experimental values of outlet air temperature of the solar air heater. Maximum instantaneous collector efficiency of 37% is obtained in the present study.