scholarly journals Performance Evaluation of an Evacuated Tube Collector with a Low-Cost Diffuse Reflector

Energies ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 8209
Author(s):  
Julian Schumann ◽  
Bert Schiebler ◽  
Federico Giovannetti
Keyword(s):  
Ray Tracing ◽  
Incident Angle ◽  
Low Cost ◽  
Water System ◽  
Incident Radiation ◽  
Hot Water ◽  
Rear Side ◽  
Collector Efficiency ◽  
Evacuated Tube Collectors ◽  
Evacuated Tube

In order to increase the overall solar energy gain of evacuated tube collectors, rear-side reflectors are used. In this way, the otherwise unused incident radiation between the tubes can be reflected back to the absorber, and the performance of the collector can be improved. In this paper, the use of a low-cost, diffusely reflecting, trapezoidal roof covering made from a galvanized metal sheet is investigated and compared to a high-quality, specularly reflecting plane reflector made of aluminum. For this purpose, ray-tracing analysis and TRNSYS simulations were carried out. In the ray-tracing analysis, the experimentally determined zero-loss collector efficiency η0 as well as the incident angle modifiers for each reflector can be reproduced with an error lower than 7.5%. Thermal system simulations show that the performance of both reflectors is comparable. The use of the low-cost reflector leads to an increase in annual collector output of around 30% compared to an increase with the specular reflector of around 33%. Considering a typical domestic hot water system, both reflectors enable an increase in the solar annual yield of approx. 11%.

scholarly journals Evaluating the Performance of Two Solar Domestic Hot Water Systems of the Archetype Sustainable Houses

2021 ◽  
Author(s):  
Kamyar Tanha
Keyword(s):  
Flat Plate ◽  
Hot Water ◽  
Experimental Results ◽  
Solar Thermal ◽  
Energy Output ◽  
Evacuated Tube Collector ◽  
Solar Thermal Collector ◽  
Solar Thermal Collectors ◽  
Evacuated Tube Collectors ◽  
Evacuated Tube

This thesis is focused on the performance of the two SDHW systems of the sustainable Archetype houses in Vaughan, Ontario with daily hot water consumption of 225 litres. The first system consists of a flat plate solar thermal collector in conjunction with a gas boiler and a DWHR. The second SDHW system consists of an evacuated tube collector, an electric tank and a DWHR. The experimental results showed that the DWHRs were capable of an annual heat recovery of 789 kWh. The flat plate and evacuated tube collectors had an annual thermal energy output of 2038 kWh and 1383 kWh. The systems were also modeled in TRNSYS and validated with the experimental results. The simulated results showed that Edmonton has the highest annual energy consumption of 3763.4 kWh and 2852.9 kWh by gas boiler and electric tank and that the solar thermal collectors and DWHRs are most beneficial in Edmonton.

Evaluating CFD Modeling of a Thermal Storage Unit

2010 ◽  
Author(s):  
Monica F. Bonadies ◽  
Son H. Ho ◽  
J. S. Kapat
Keyword(s):  
Thermal Energy ◽  
Photovoltaic Cells ◽  
Thermal Storage ◽  
Hot Water ◽  
Paraffin Wax ◽  
Heat Transfer Fluid ◽  
Cfd Modeling ◽  
Storage Unit ◽  
Evacuated Tube Collectors ◽  
Evacuated Tube

When collecting the energy of the sun for domestic use, there are several options, which include photovoltaic cells and evacuated tube collectors. Arrays of evacuated tube collectors are used to heat water for domestic applications, supplementing the use of a typical hot water heater, while photovoltaic cells transform the sun’s radiation into electricity. The benefit of the tube collectors is that they supplement an appliance that uses a fairly large amount of electricity when compared to others in an average home. However, the collectors cannot operate during the night time and produce more hot water than needed at their peak operation point. A thermal storage unit can be used to even out the conversion of energy throughout the day to solve this problem. This study proposes a system using paraffin wax to store thermal energy collected during the day by melting the wax. The system makes use of a finned heat exchanger, with paraffin wax on the shell side, and glycol on the tube side as the heat transfer fluid. It also includes a separate loop for water to flow through and receive thermal energy from the melted wax. Although the wax used in the study is quite effective at storing thermal energy, it has the problem of low conductivity. So, fins are added to the storage and extraction loops to increase the wax’s thermal conductivity. The fins not only help to melt the wax more quickly but also act as nucleation sites when the wax freezes. Once all the wax is melted, energy can be exchanged from it to heat water. When creating such a unit, it is useful to have simulation tools to guide its design. One such tool is FLUENT, which will be used in this study to create a simulation of part of the unit. The simulation will be compared to experimental data from a prototype unit and evaluated based upon its strengths and weaknesses.

scholarly journals The Comparison of Solar Energy Gaining Effectiveness between Flat Plate Collectors and Evacuated Tube Collectors with Heat Pipe: Case Study

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1829 ◽  
Author(s):  
Piotr Olczak ◽  
Dominika Matuszewska ◽  
Jadwiga Zabagło
Keyword(s):  
Solar Energy ◽  
Flat Plate ◽  
Heat Pipe ◽  
Hot Water ◽  
Energy Productivity ◽  
External Conditions ◽  
Evacuated Tube Collectors ◽  
Evacuated Tube ◽  
Family House

In Poland, various solar collector systems are used; among them, the most popular are flat plate collectors (FPCs) and evacuated tube collectors (ETCs). The work presents two installations located at a distance of 80 km apart, working in similar external conditions. One of them contains 120 flat plate collectors and works for the preparation of hot water in a swimming pool building; the second one consists of 32 evacuated tube collectors with a heat pipe and supports the preparation of domestic hot water for a multi-family house. During the comparison of the two quite large solar installations, it was confirmed that the use of evacuated tube solar collectors shows a much better solar energy productivity than flat plate collectors for the absorber area. Higher heat solar gains (by 7.9%) were also observed in the case of the gross collector area. The advantages of evacuated tube collectors are observed mainly during colder periods, which allows for a steadier thermal energy production.

A Numerical Simulation Study for the Performance of a Multi-Purpose Large Solar Hot Water System Operated in Taiwan

2016 ◽  
Author(s):  
Ru Yang ◽  
Yu-Ting Yen
Keyword(s):  
Simulation Study ◽  
Air Conditioning ◽  
Storage Capacity ◽  
Water System ◽  
Hot Water ◽  
Climate Data ◽  
Domestic Hot Water ◽  
Computer Simulation Program ◽  
Heating Load ◽  
Evacuated Tube

There is rich solar energy in Taiwan, it also has a great developing potential for solar applications. Solar hot water is able to supply the domestic hot water, the heating load, and the driving energy for absorption cooing. In this paper, a computer simulation program for a multi-purpose solar hot water system providing hot water, winter heating and summer air-conditioning is established by TRNSYS program. Simulation study is done with varying parameters including collector area, storage capacity and type of collector (flat plate and evacuated tube). In order to study the system performance in Taiwan, system simulations are made under the climate data of three representative cities (Taipei in north, Taichung in central, and Kaohsiung in southern) of Taiwan. The results of the present study can provide important reference for the development of the multi-purpose solar hot water system.

Investigation of Evacuated Tube Collector Performance at High Temperature Mode Using TRNSYS Simulation Model

2013 ◽  
Vol 465-466 ◽  
pp. 155-160
Author(s):  
Basil H. Ali ◽  
S.I. Gilani ◽  
Hussain Hamoud Al-Kayiem
Keyword(s):  
Simulation Model ◽  
Substantial Improvement ◽  
High Concentration ◽  
Evacuated Tube Collector ◽  
Temperature Mode ◽  
Collector Efficiency ◽  
Good Improvement ◽  
Evacuated Tube Collectors ◽  
Evacuated Tube ◽  
Different Levels

It has been proved that creation of vacuum between the absorber and the cover of a solar collector is resulting in a substantial improvement in the collector efficiency due to reduction in the heat loss through convection ad conduction. In this work, the performance of evacuated tube collectors is investigated using TRNSYS simulation model. Different levels of concentrations have been considered in the simulation to predict the power generation. The simulation results showed that the thermal performance of evacuated tube collectors with high concentration ratio can provide a good improvement to the receiver output.

Parametric Study of a Flat Plate Wick Assisted Heat Pipe Solar Collector

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Brahim Taoufik ◽  
Mhiri Foued ◽  
Jemni Abdelmajid
Keyword(s):  
Flat Plate ◽  
Heat Pipe ◽  
Solar Collector ◽  
Solar Collectors ◽  
Absorber Plate ◽  
Steady State Condition ◽  
Collector Efficiency ◽  
Evacuated Tube Collectors ◽  
Gap Spacing ◽  
Evacuated Tube

The use of heat pipes in solar collectors offers several advantages regarding flexibility in operation and application, as they are very efficient in transporting heat even under a small temperature difference. Compared with other systems powered by evacuated tube collectors or flat plate solar collectors using a wickless heat pipe, little attention has been paid to a flat plate solar collectors wick assisted heat pipe. In this paper an analytical model based on energy balance equations assuming a steady state condition was developed to evaluate the thermal efficiency of a flat plate wick assisted heat pipe solar collector. Parameters which affect the collector efficiency are identified, such as tube spacing distance, gap spacing between the absorber plate and the glazing cover, and the emissivity of the absorber plate. The results reflect the contribution and significance of each of these parameters to the collector overall heat loss coefficients. Three heat pipe working fluids are examined and results show that acetone performs better than methanol and ethanol.

scholarly journals Decoupling the Monitoring of Solar Water Heaters and their Usage Profiles

Water ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 3186
Author(s):  
Julian C. Nwodo ◽  
Ochuko K. Overen ◽  
Edson L. Meyer
Keyword(s):  
Low Cost ◽  
Hot Water ◽  
Housing Sector ◽  
Water Heating ◽  
Solar Water Heating ◽  
Solar Water ◽  
Water Heaters ◽  
Low Cost Housing ◽  
Solar Water Heaters ◽  
Evacuated Tube

South Africa is the most technologically advanced nation in Africa. However, the country is plagued with constant load shedding. The country receives about 2500 sunshine hours annually, with daily average irradiation levels of 4.5–6.5 kWh/m2. Despite these potentials, the use of electricity for domestic water heating is still prevalent in the country. The mass rollout of solar water heating (SWH) technologies in the low-cost housing sector across the country were met with massive failures. This study aims to assess the energy yield of a passive flat plate and an evacuated tube solar water heating system by evaluating the performance of these systems to address the energy crisis in South Africa. The flat plate (FP) and evacuated tube (ET) solar water heating systems were monitored for four days, characterised by varying sky conditions through instantaneous data measurement at 5 s. The parameters measured were water temperature, ambient temperature, irradiance at the plane of array, relative humidity, wind speed and direction. The results obtained show that a maximum irradiance of 1050 W/m2 was obtained on a clear day and corresponded to a hot water temperature of about 58 °C and 65 °C for the FP and ET, respectively. However, a cloudy day with a maximum irradiance of 400 W/m2 produced about 22 °C and 29 °C of hot water for the FP and ET, respectively. The results obtained in this study will guide stakeholders in the renewable energy sector towards employing SWH systems to replace or augment the electric geyser. Solar water heaters (SWH) can be used in the low-cost housing sector to provide hot water. Hence, the assessments in this study offer essential information for the deployment of these systems to reduce demand on the ailing South African electricity utility, Eskom, and mitigate climate change.

Sign in / Sign up

Export Citation Format

Share Document