Evacuated Tube Heat Pipe Solar Collectors Applied to Recirculation Loop in a Federal Building: SSA Philadelphia

Author(s):  
Andy Walker ◽  
Fariborz Mahjouri ◽  
Robert Stiteler

This paper describes design, simulation, construction and measured initial performance of a solar water heating system (360 Evacuated Heat-Pipe Collector tubes, 54 m2 gross area, 36 m2 net absorber area) installed at the top of the hot water recirculation loop in the Social Security Mid-Atlantic Center in Philadelphia. Water returning to the hot water storage tank is heated by the solar array when solar energy is available. This new approach, as opposed to the more conventional approach of preheating incoming water, is made possible by the thermal diode effect of heat pipes and low heat loss from evacuated tube solar collectors. The simplicity of this approach and its low installation costs makes the deployment of solar energy in existing commercial buildings more attractive, especially where the roof is far removed from the water heating system, which is often in the basement. Initial observed performance of the system is reported. Hourly simulation estimates annual energy delivery of 111 GJ/year of solar heat and that the annual efficiency (based on the 54 m2 gross area) of the solar collectors is 41%, and that of the entire system including parasitic pump power, heat loss due to freeze protection, and heat loss from connecting piping is 34%. Annual average collector efficiency based on a net aperture area of 36 m2 is 61.5% according to the hourly simulation.

A completed study of a solar hot water heating system installed in a school showed an annual average efficiency of 15%, the low efficiency largely caused by the unfavourable pattern of use in schools. Field studies, in 80 existing and 12 new houses, of a simple domestic hot water system have been initiated to ascertain the influence of the occupants on the actual performance of solar collector systems. The development of testing methods of solar collectors and solar water heating systems is being undertaken in close collaboration with the B.S.I. and the E.E.C. Solar space heating is being investigated in two experimental low energy house laboratories, one using conventional solar collectors with interseasonal heat storage and the other a heat pump with an air solar collector. Studies of the cost-effectiveness of solar collector applications to buildings in the U.K. show that they are far less cost-effective than other means of conserving energy in buildings.


Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1829 ◽  
Author(s):  
Piotr Olczak ◽  
Dominika Matuszewska ◽  
Jadwiga Zabagło

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.


Author(s):  
Enrico Zambolin ◽  
Davide Del Col ◽  
Andrea Padovan

New comparative tests on different types of solar collectors are presented in this paper. Tests have been performed at the solar energy conversion laboratory of the University of Padova. Two standard glazed flat plate collectors and one evacuated tube collector are installed in parallel; the evacuated collector is a direct flow through type with external CPC (compound parabolic concentrator) reflectors. The present test rig allows to make measurements on the flat plate, on the evacuated collector or on both simultaneously, by simply acting on the valves to modify the circuit. In this paper measurements of the performance of the evacuated tube collector and flat plate collectors working at the same conditions are reported. Efficiency in stationary conditions is measured following the standard EN 12975-2 [1] and it is compared with the input/output curves measured for an entire day. The main purpose of the present work is to characterize and to compare the daily energy performance of the two types of collectors. An effective mean for describing and analyzing the daily performance is the so called input/output diagram, in which the collected solar energy is plotted against the daily incident solar radiation. Test runs have been performed in several conditions to reproduce different conventional uses (hot water, space heating, solar cooling).


2013 ◽  
Vol 724-725 ◽  
pp. 163-170
Author(s):  
Zhang Yuan Wang ◽  
Xiang Mei Zhang ◽  
Wan Sheng Yang ◽  
Zhi Wu Chen

In this paper, a novel solar water heating system will be proposed by applying the loop heat pipe to a conventional split solar hot water system, which will have the characteristics of high efficiency, low cost, appearance appealing and building integration. Three types of the system, i.e., the system with evacuated tubes, with single flat-plate glazing cover, and without glazing, will be experimentally investigated and compared on the influence to the dynamic performance of the system. It was found that the system’s operating temperature increased significantly during the start-up stage and gently after until reach relatively constant. The instantaneous efficiency was found to be fluctuated, although it reached stable eventually during the operations for all three types. By using the moving average calculating method, every 10 minutes were applied for the calculation of the average efficiency which had a negative linear relation with the combined factor of (Tmean-Tamb)/I. In general, the solar system with evacuated tubes performed the best with the highest water temperature output, highest system efficiency and lowest heat loss coefficient among the three systems.


Processes ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 1536
Author(s):  
Xilian Han ◽  
Chao Li ◽  
Hongqiang Ma

This paper proposed an experimental test: the solar water-heating system was been monitored for a whole year to analyze collector performance in an actual operation process. Heat-collecting efficiency, heating capacity, power consumption, and heat required were analyzed theoretically. Results showed that solar irradiance and ambient temperature were positively correlated with heat collection efficiency, and the daily average heat collection efficiency was up to 56.63%. In winter, the auxiliary heat source consumed the most power, almost all of which bears the heat of users. The heat collection in summer met the demand for hot water, and the guarantee rate of solar energy could reach 100%. The energy saving properties and CO2 emission reduction were analyzed. This system had a significant effect on the energy-saving effect and environmental protection. The analysis showed that the hot-water system can fully meet the design requirements under the condition of relatively sufficient solar energy, and can operate stably, which has a certain guiding significance for the design and application of large-scale solar hot-water systems.


2015 ◽  
Vol 121 ◽  
pp. 1544-1555
Author(s):  
Mingzhi Jiang ◽  
Guohui Feng ◽  
Kailiang Huang ◽  
Shibo Liu ◽  
Dong Liang ◽  
...  

Solar Energy ◽  
2006 ◽  
Author(s):  
Peter E. Zemke ◽  
Byard D. Wood

Hybrid solar lighting (HSL) has been successfully demonstrated as a means of collecting sunlight and transferring it through optical fibers into a building. The collected solar energy is primarily intended for illumination purposes. However, this technology may have an application in solar water heating. For a traditional solar water heating system, energy is required to pump the water to the roof and collected solar energy is lost to the environment through the collector and plumbing. If such a system is to be used in climates where the temperature falls below freezing, complexity is added resulting in lower system efficiencies. If, rather than pumping water to the roof to absorb solar energy, the solar radiation is “piped” into the hot water store, a solar water heating system may be much less complex and potentially more efficient. HSL technology can be used to collect solar radiation and transport it through optical fibers into a hot water store. Since the water remains in the tank, it is not exposed to freezing temperatures and heat loss through plumbing. The efficiency of the system would not be dependent on the outside temperature or the temperature of the water as traditional systems are, but solely on the efficiency in which solar radiation is transferred into the water. This paper will outline the major advantages of using HSL technology for solar water heating over traditional systems. The approximate efficiencies of a flat-plate collector, 2-axis solar tracking collector, and a system using HSL technology are compared using F-Chart for locations in the Southwestern and Northeastern United States. It is shown that improvements in efficiency are obtained using HSL technology if the system is capable of collecting and transferring the visible and infrared spectrum of solar radiation.


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