Evacuated Tube Collectors (ETC)

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Adapting Integrated High Concentrated PV Modules and Evacuated Tube Collectors to Minimize Building Energy Consumption in Hot Climate

Adapting Integrated High Concentrated PV Modules and Evacuated Tube Collectors to Minimize Building Energy Consumption in Hot Climate

Energy consumption in buildings is considered a significant portion of gross power dissipation, so a great effort is required to design efficient construc- tion. In severe hot weather conditions as Kuwait, energy required for building cooling and heating results in a huge energy loads and consumption and ac- cordingly high emission rates of carbon dioxide. So, the main purpose of the current work is to convert the existing institutional building to near net-zero energy building (nNZEB) or into a net-zero energy building (NZEB). A com- bination of integrated high concentrated photovoltaic (HCPV) solar modules and evacuated tube collectors (ETC) are proposed to provide domestic water heating, electricity load as well as cooling consumption of an institutional fa- cility. An equivalent circuit model for single diode is implemented to evaluate triple junction HCPV modules efficiency considering concentration level and temperature effects. A code compatible with TRNSYS subroutines is intro- duced to optimize evacuated tube collector efficiency. The developed models are validated through comparison with experimental data available from lite- rature. The efficiency of integrated HCPV-ETC unit is optimized by varying the different system parameters. Transient simulation program (TRNSYS) is adapted to determine the performance of various parts of HCPV-ETC sys- tem. Furthermore, a theoretical code is introduced to evaluate the environ- mental effects of the proposed building when integrated with renewable energy systems. The integrated HCPV-ETC fully satisfies the energy required for building lighting and equipment. Utilizing HCPV modules of orientation 25˚ accomplishes a minimum energy payback time of about 8 years. Integrated How to cite this paper: Alzanki, T.H. and
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Validated TRNSYS model for forced circulation solar water heating systems with flat plate and heat pipe evacuated tube collectors

Validated TRNSYS model for forced circulation solar water heating systems with flat plate and heat pipe evacuated tube collectors

A TRNSYS model was developed for forced circulation solar water heating systems with flat plate and heat pipe evacuated tube collectors. The model was validated using field trial data for systems installed in Dublin, Ireland. Results obtained showed that the model predicted the collector outlet fluid temperature with percentage mean absolute error (PMAE) of 16.9% and 18.4% for the FPC and ETC systems respectively. Heat collected and delivered to the load was also predicted with PMAE of 14.1% and 6.9% for the FPC system and 16.9% and 7.6% for the ETC system respectively. The model underestimated the collector outlet fluid temperature by -9.6% and overestimated the heat collected and heat delivered to load by 7.6% and 6.9% for the FPC system. The model overestimated all three parameters by 13.7%, 12.4% and 7.6% for the ETC system.
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Experimental and Theoretical Investigation of Evacuated Tube Solar Collector with Heat Pipe

Experimental and Theoretical Investigation of Evacuated Tube Solar Collector with Heat Pipe

There are different methods to harness the solar energy one such process is the solar thermal collectors which can trap the radiation and convert into thermal energy and transfer it to the working liquid. Flat plate collectors are subjected to heat loss which is minimized in ETC.[1] Evacuated tube consists of two glass tubes made of borosilicate the inner glass tube and outer tubes are separated by vacuum space. The vacuum is a perfect insulator doesn’t allow the short wave radiation to escape through vacuum characteristics of trapping radiation is better than other methods. The Evacuated tube collectors have two tubes separated by a vacuum where the radiant energy incident can be directed inside the tube without much heat losses [2]. Heat pipe is a thermal energy absorbing and transferring system with no moving parts which can transfer more energy than copper, where the heat pipes are the best known conductor. Heat pipe can operate with a temperature up to 300 ○ C with 50% to 60% efficiently [3]. The solar radiation incident on the collector of the outer glass the short radiation is incident on the inner tube consists of the heat pipe where the radiation falls on the external surface of the heat pipe and causes the working fluid near the surface to evaporate instantaneously. The vapour thus formed absorbs latent heat of vaporization and this part is evaporator region then vapour travels to other end of pipe causing vapour to condense this part is condenser region giving up the heat (thermal energy) to the manifold where the heat is exchanged with cold fluid passing through the manifold.
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Evacuated U-Tube Solar Water Heating System- A Descriptive Study

Evacuated U-Tube Solar Water Heating System- A Descriptive Study

Copyright to IJIRSET www.ijirset.com 12628 A Solar Water Heating System (SWHS) utilizes the incident solar radiation and convert it in to thermal energy for heating the water to use in various applications [2]. The Solar Water Heating System consists of solar thermal collectors, water tanks, interconnecting pipelines, and the water, which gets circulated within the solar water heating system. Sun rays falling on the collector tube which then heats the tube, thereby transferring the heat energy to water flowing through it. The two popular devices that are used for water heating are Flat Plate Collectors (FPC) and Evacuated Tube Collectors (ETC). Since 2000, the arrival of ETC has had a significant impact on the SWH market. As per MNRE data, in the year 2008-09, ETC constituted more than 30% of the total sales. On July 1, 2009, there were 61 MNRE approved ETC suppliers and manufacturers. The arrival of Evacuated Tube Collector has resulted in expanding the Solar Water Heating supply chain significantly. It has also resulted in reduction in costs of the domestic SWH systems.Morrison et al has [5] reported that evacuated tube solar collectors perform better than flat plate collectors during
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An Overview of Solar Thermal Power Generation Systems

An Overview of Solar Thermal Power Generation Systems

There are two types of solar collectors: non- concentrating or stationary collectors and concentrating ones. A non-concentrating collector has the same area for intercepting and absorbing solar radiation, whereas a sun-tracking concentrating solar collector usually has parabolic reflecting surfaces to intercept and focus the sun’s beam radiation to a smaller receiving area, which is called the absorber. Therefore, the radiation flux will be increased. In contrast, stationary collectors are fixed in position and do not track the sun. They are often classified into three types of flat plate collectors (FPC), evacuated tube collectors (ETC) and, compound parabolic collectors (CPC). On the other hand, concentrated collectors track the sun and only are able to capture direct solar radiation either onto a point such as parabolic dish concentrator (PDC) and solar towers or onto a linear receiver such as parabolic trough concentrator (PTC) and linear Fresnel reflectors (LFR) [3].
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Use Solar Heat for Prosperity, Healthy and Pollution Free Life

Use Solar Heat for Prosperity, Healthy and Pollution Free Life

A solar water heater consists of collector to collect solar energy, insulated storage tank and pipelines. The solar energy incident on absorber panel coated with selected coating transfer the heat to riser pipes underneath the absorber panel. The water passing through the risers get heated and delivered to storage tank. The re- circulation of same water through absorber panel in the collector raises the temperature up to 80 0 C. There are two types of water heater, flat plate collectors and evacuated tube collectors. The solar radiation is absorbed in Flat Plate Collectors (FPC). FPC is consisting of an insulated outer metallic box covered on the top with glass sheet. Inside there are blackened metallic absorber (selectively coated) sheets with built in channels or riser tubes to carry out water. The absorber absorbs solar radiation and transfer heat to flowing water. Evacuated tube collector is made of double layer borosilicate glass tubes evacuated for providing insulation. The outer wall of inner tube is coated with selective absorbing material. This helps absorption of solar radiation and transfer heat to the water which flow in inner tube.
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A REVIEW ON SOLAR THERMOELECTRIC COGENERATOR WITH EVACUATED TUBE SOLAR COLLECTOR

A REVIEW ON SOLAR THERMOELECTRIC COGENERATOR WITH EVACUATED TUBE SOLAR COLLECTOR

From this review, various ways of using thermoelectric power generation system were reviewed. The most efficient way for improving the performance of thermoelectric power generation systems is to use it with hybrid systems. As discussed in this paper thermoelectric module can be used with flat plate collectors, parabolic collectors and pabolic dish or evacuated tube collectors to generate heat and electricity simultaneously. Such hybrid system improves the overall performance of the thermoelectric power generation system which can be made cost effective.
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Performance and operational effectiveness of evacuated flat plate solar collectors compared with conventional thermal, PVT and PV panels

Performance and operational effectiveness of evacuated flat plate solar collectors compared with conventional thermal, PVT and PV panels

The parabolic trough collector in Fig. 7 (PolyTrough 1800) [46] has a concentration factor of 54. Its e ffi ciency curve was taken from the manufacturer ’ s data sheet as a DIN CERTCO certi fi cate was unavailable. The gross area in Fig. 7 was estimated for vertical illumination, as- suming the closest trough pitch (2 m) allowing full rotation without interference. Trough arrays are generally arranged in a horizontal plane whereas flat plate and evacuated tube collectors are usually mounted on a sloping roof. At lower incidence angles the PTC fill factor increases slightly, improving the e ffi ciency and moving the intercept with the EFP curve down to T M = 210 C ° .
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Design and Fabrication of Parabolic Trough Collector Using Modified Evacuated Tube

Design and Fabrication of Parabolic Trough Collector Using Modified Evacuated Tube

The Evacuated tube collector consists of a number of rows of parallel transparent glass tubes connected to a header pipe and which are used in place of the blackened heat absorbing plate we saw in the previous flat plate collector. These glass tubes are cylindrical in shape. Evacuated tube collectors do not heat the water directly within the tubes. Instead, air is removed or evacuated from the space between the two tubes, forming a vacuum (hence the name evacuated tubes). This vacuum acts as an insulator reducing any heat loss significantly to the surrounding atmosphere either through convection or radiation making the collector much more efficient than the internal insulating that flat plate collectors have to offer. With the assistance of this vacuum, evacuated tube collectors generally produce higher fluid temperatures than their flat plate counterparts so may become very hot in summer.
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Review on Evacuated Glass Tube Based Solar Liquid Heaters

Review on Evacuated Glass Tube Based Solar Liquid Heaters

Ayompe et al. [38] monitored year round energy performance of solar water heaters with 4 m 2 flat plate and 3 m 2 heat pipe evacuated tube collectors under same operating conditions. The annual collector efficiency observed were 46.1% and 60.7% for the flat plate collector and evacuated tube collector respectively with system efficiencies of 37.9% and 50.3% for the same systems. Economic analysis showed that both solar water heating systems were not economically viable because of their very low net present worth and their simple payback periods varied between 13 years and 48.5 years of flat plate collector and evacuated pipe collector respectively. Liang et al. [39] have carried out study and experiment on the filled type evacuated tube, in which filled layer was used to transfer energy absorbed by the working fluid flowing in the U-tube. The effects of heat loss co-efficient and the thermal conductivity of the filled layer on the thermal performance of the evacuated tube were analyzed and efficiency of evacuated tube was calculated. It was found that filled type evacuated tube with U-tube had favourable thermal performance and efficiency observed was 12% higher than that of the U-tube evacuated tube with a copper fin. Chow et al. [40] experimentally and numerically evaluated performance of the two common types of evacuated tube solar water heater single phase open thermosyphon system and two phase closed thermosyphon system. Result showed that daily and annual thermal performances of two phased Thermosyphon system was slightly better than single phase open thermosyphon system but payback periods for two of them were relatively same because of high initial cost so they proved to be less economical then flat plate collector. They may be suitable for the advanced systems with higher temperature demands. Abdul Waheed Badar et al. [41] analysed vacuum tube solar collector with co-axial piping (direct flow type) incorporating both single and two phase flows for different heat transfer mechanisms and flow conditions. Results have shown that for all liquid single phase fluid flow, the collector efficiency decreases with decreasing mass flow rate. No significant reduction in efficiency was observed under partial stagnation. Testing of three thermosyphon heat pipe evacuated tube solar water heater for pumped fluid circulation was carried out by David A.G. Redpath [42]. Thermosyphon evacuated tube solar water heaters both with same area of 2 m 2 was monitored. In which one utilized internal heat pipe condensers while other used external ones. The system with internal condensers was found to be 17 % more efficient.
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Simulation of Convection Flow and Sensitivity Analysis of Model Parameters of Evacuated Glass Tube Solar Water Heater

Simulation of Convection Flow and Sensitivity Analysis of Model Parameters of Evacuated Glass Tube Solar Water Heater

The evacuated-tube solar collectors are costlier than the flat-plate collectors; however, their temperature gained is higher than the flat-plate collectors. Evacuated-tube collectors are made up of rows of parallel, transparent glass tubes. Each tube consists of a glass outer tube and an inner tube, or absorber, covered with a selective coating that absorbs solar energy well but inhibits radiative heat loss. The air is withdrawn (evacuated.) from the space between the tubes to form a vacuum, which eliminates conductive and convective heat loss [8].
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Constant temperature induced stresses in evacuated enclosures for high performance flat plate solar thermal collectors

Constant temperature induced stresses in evacuated enclosures for high performance flat plate solar thermal collectors

The mechanical design of a VFP collector has to with- stand atmospheric pressure forces applied to its exterior surface. Mechanical stress in flat, rectangular, evacuated enclosures has been investigated previously for vacuum glazing applications (Fischer-Cripps et al., 1995; Simko et al., 1998; Wang et al., 2007). Vacuum glazing consists of two sheets of glass separated by an array of very small structural support pillars, typically less than 0.5 mm in both height and diameter. A seal is made around the periphery of the glass sheets and the small interior volume is evacuated to a high vacuum (less than 0.1 Pa), resulting in a narrow building component with a U-value less than 1 W/m 2 K, if low emissivity coatings are used to suppress radiative heat transfer. However, the glass sheets are sub- ject to large, sustained stresses from atmospheric pressure loading over their surfaces and from differential thermal expansion when one glass sheet is warmer than the other. Evacuated enclosures for flat plate solar thermal collec- tors have design similarities to vacuum glazing, but are subject to different design constraints and operational con- ditions as there are more mechanical design options. The purpose of this paper is to explore various fundamental design options and describe their effects on the mechanical stresses.
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Drying Kinetics of Muscat Grapes in a Solar Drier with Evacuated Tube Collector

Drying Kinetics of Muscat Grapes in a Solar Drier with Evacuated Tube Collector

A solar drier assisted with evacuated tube collector is designed and developed to study and examine the drying Kinetics of muscat grapes in Thanjavur, Tamilnadu, India. During the drying period, temperature at various places, relative humidity, wind velocity and mass of the sample are measured on hourly basis. The outlet temperature of the collector and temperature within the chamber varies from 74-130 ºC and 50- 87 ºC respectively, while the ambient temperature ranges from 29.5-33.2 ºC. Solar insulation recorded during these days ranges from 155.6-1115 W/m 2 . The designed drier takes 14 hours to reduce the
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New Technique for Water  Desalination Using Novel Solar Still And  Parabolic Trough Collector

New Technique for Water Desalination Using Novel Solar Still And Parabolic Trough Collector

Mohammad al-harahsheh et al. had studied solar desalination using solar still enhanced by external solar collector and PCM. They fabricate the solar still using stainless steel with basin area 1meter square. Glass with thickness 1 cm covered on solar still at angle 36 degree.solar still is coupled with solar collectors and used PCM material in the solar still. From their experiment, they concluded that PCM worked to supply energy during the night time period without any change in thermal behavior and the highest daily productivity of the unit achieved experimentally was 4300 ml/day-meter square.[15]
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Experimental Analysis on Thermal Efficiency of Evacuated Tube Solar Collector by Using Nanofluids

Experimental Analysis on Thermal Efficiency of Evacuated Tube Solar Collector by Using Nanofluids

efficiency of solar collector in comparison with water as working fluid by 31.64%. Otanicar and Golden [15] reported the experimental results on solar collector based on nanofluids composed of a variety of nano particles (carbon nano tubes, graphite, and silver). The efficiency improvements were up to 5% in solar thermal collectors by utilizing nanofluids as the absorption mechanism. The experimental and numerical results demonstrated an initial rapid increase in efficiency with volume fraction, followed by a leveling off in efficiency as volume fraction continues to increase. Yousefi et al. [16,17] studied the effect of Al 2 O 3
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Numerical Analysis Of Thin Layer Drying Kinetics Of Untreated Carrot Slices Using Photovoltaic Thermal Solar Dryer

Numerical Analysis Of Thin Layer Drying Kinetics Of Untreated Carrot Slices Using Photovoltaic Thermal Solar Dryer

performance of the photovoltaic thermal hybrid solar dryer assisted with ETC increases the drying rate. The initial moisture content of the untreated carrot slices determined using hot air oven is 85% (wb). The photovoltaic thermal hybrid dryer takes 8 hours to reach the final moisture content of 9.3% (wb) which is observed to be the closet moisture content for safe storage. Sun drying takes 14 hours to reach the equilibrium moisture content of 9.5%. Figure 3.1 and 3.2 shows the variation of moisture content with respect to drying time and variation of moisture ratio with respect to drying time respectively for both PV – Thermal hybrid solar dryer and sun drying of untreated carrot.
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PERFORMANCE ANALYSIS OF PARABOLIC TROUGH SOLAR COLLECTOR FOR THREE DIFFERENT FLOW RATES

PERFORMANCE ANALYSIS OF PARABOLIC TROUGH SOLAR COLLECTOR FOR THREE DIFFERENT FLOW RATES

The design of parabolic trough collectors are structurally simpler than other types of but it requires continuous tracking so as to make sure that solar radiations are concentrated on the absorber tube throughout the day. The design of PTSC should be precise and the dimensions on x, y directions must be accurate to ensure the better optical efficiency of the system.

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DEVELOPMENT OF COST EFFECTIVE SOLAR THERMOELECTRIC COGENERATOR WITH EVACUATED TUBE SOLAR COLLECTOR

DEVELOPMENT OF COST EFFECTIVE SOLAR THERMOELECTRIC COGENERATOR WITH EVACUATED TUBE SOLAR COLLECTOR

The design of the thermoelectric generator was started with main support structure, which is used to mount thermoelectric modules, the evacuated tube solar collector and the cooling water tank. In the present design support structure body, makes the indirect support hot side of the thermoelectric generator module. The support structure design in the thermoelectric power generator is quite critical because in a very short time the energy (heat) should transfer from source to hot side of the thermoelectric generator module also this design should be such that it should not affect the performance of the cooling arrangement at cold of the thermoelectric generator modules.
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A review of integrated phase change materials for evacuated tube solar collector system

A review of integrated phase change materials for evacuated tube solar collector system

The integration of PCM with solar thermal systems means either by developing TES in the collector, in the water tank or in a separate container. The integrated TES-ETSC system was achieved by developing the storage in the header (manifold) [studied by Naghavi et al., (2015); Mehla and Yadav, (2015); Mehla and Yadav, (2016)] or achieved inside the inner cavity (in-tube) [studied by Papadimitratos et al., (2016); Xue, (2016); Abokersh et al., (2017)], refer to Figure 1. Interestingly, Papadimitratos and others (Papadimitratos et al., 2016) incorporated organic materials: Tritriacontane with a 72°C melting temperature and Erythritol with a 118°C melting temperature, into the ETSC system in order to address the evening peak demand. They claimed an efficiency improvement of 26% compared with a
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Performance and Optimization of a Small Hybrid Solar Thermal Collector

Performance and Optimization of a Small Hybrid Solar Thermal Collector

Evacuated tube solar collectors are composed of the evacuated tubes themselves, a heat pipe, and a manifold. When placed in sunlight, the tubes absorb solar energy and convert it to heat while utilizing the vacuum-sealed area between the two glass layers as an insulator to prevent heat loss. The copper heat pipe within the tubes manifests into a copper bulb at the top of the tubes. Within the heat pipes a liquid is evaporated and condensed using heat from the sun. As the liq- uid evaporates, it rises through the heat pipe where it transfers its heat to the ETC working fluid passing over the bulbs and falls to the base of the heat pipe as it condenses. In the hybrid system, this heat transfer takes place in the manifold, an insulated box containing the bulbs at the top of the heat pipes, and with the working fluid of the system passing over the bulbs [3].
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