Thermal Performance of a Large Low Flow Solar Heating System With a Highly Thermally Stratified Tank

2005 ◽  
Vol 127 (1) ◽  
pp. 15-20 ◽  
Author(s):  
Simon Furbo ◽  
Niels Kristian Vejen ◽  
Louise Jivan Shah

In year 2000 a 336 m2 solar domestic hot water system was built in Sundparken, Elsinore, Denmark. The solar heating system is a low flow system with a 10000 l hot-water tank. Due to the orientation of the buildings half of the solar collectors are facing east, half of the solar collectors are facing west. The collector tilt is 15° from horizontal for all collectors. Both the east-facing and the west-facing collectors have their own solar collector loop, circulation pump, external heat exchanger and control system. The external heat exchangers are used to transfer the heat from the solar collector fluid to the domestic water. The domestic water is pumped from the bottom of the hot-water tank to the heat exchanger and back to the hot-water tank through stratification inlet pipes. The return flow from the DHW circulation pipe also enters the tank through stratification inlet pipes. The tank design ensures an excellent thermal stratification in the tank. The solar heating system was installed in May 2000. The thermal performance of the solar heating system has been measured in the first two years of operation. Compared to other large Danish solar domestic hot water systems the system is performing well in spite of the fact that the solar collectors are far from being orientated optimally. The utilization of the solar radiation on the collectors is higher, 46% in the second year of operation, than for any other system earlier investigated in Denmark, 16%–34%. The reason for the good thermal performance and for the excellent utilization of the solar radiation is the high hot-water consumption and the good system design making use of external heat exchangers and stratification inlet pipes.

2021 ◽  
Author(s):  
Jamie Fine

Society’s use of fossil fuels has led to increasingly high levels of CO2 in the atmosphere. These levels have been linked to global average temperature rises, and increases in the severity and frequency of major weather events. To combat these effects, nations around the world have committed to reducing their CO2 emissions, and transition to renewable energy. This thesis focuses on the development of a novel solar heating system, which combines a hybrid solar panel and cascade heat pump. The thesis begins by presenting a high-level literature review of solar and heat pump technologies, followed by the initial design development of the system. Two design iterations are presented, illustrating that the final design was selected because it exhibits improved peak heat output, and reduced sensitivity to panel temperature. Next, a manuscript-based chapter is presented that focuses on utilizing the proposed solar heating system for water distillation. Case studies are presented that compare the performance of the proposed system with a solar still at four different locations. The final conclusion from these studies is that using the proposed system offers area-based performance improvements of 780% compared to a basic solar still. A second manuscript-based study is then presented, which focuses on utilizing the proposed solar heating system for domestic hot water production. Additional case studies are detailed that compare the proposed system to an evacuated tube design, and a single heat pump. The conclusions from these studies are that the proposed system exceeds the performance of the evacuated tube system by up to 64%, and that the proposed system is most beneficial during seasons with higher average dry-bulb temperatures, and increased solar irradiation. A final manuscript-based study is then presented, which focuses on a methodology for improving alternate mode thermal performance estimates for hybrid solar panels. The conclusion from this study is that the proposed methodology can successfully estimate thermal performance within 5% of actual values. Each of these studies contributes to the project goal of developing a novel solar energy heating system, which can be further developed to reduce global CO2 emissions, and reduce the effects of climate change.


2021 ◽  
Author(s):  
Jamie Fine

Society’s use of fossil fuels has led to increasingly high levels of CO2 in the atmosphere. These levels have been linked to global average temperature rises, and increases in the severity and frequency of major weather events. To combat these effects, nations around the world have committed to reducing their CO2 emissions, and transition to renewable energy. This thesis focuses on the development of a novel solar heating system, which combines a hybrid solar panel and cascade heat pump. The thesis begins by presenting a high-level literature review of solar and heat pump technologies, followed by the initial design development of the system. Two design iterations are presented, illustrating that the final design was selected because it exhibits improved peak heat output, and reduced sensitivity to panel temperature. Next, a manuscript-based chapter is presented that focuses on utilizing the proposed solar heating system for water distillation. Case studies are presented that compare the performance of the proposed system with a solar still at four different locations. The final conclusion from these studies is that using the proposed system offers area-based performance improvements of 780% compared to a basic solar still. A second manuscript-based study is then presented, which focuses on utilizing the proposed solar heating system for domestic hot water production. Additional case studies are detailed that compare the proposed system to an evacuated tube design, and a single heat pump. The conclusions from these studies are that the proposed system exceeds the performance of the evacuated tube system by up to 64%, and that the proposed system is most beneficial during seasons with higher average dry-bulb temperatures, and increased solar irradiation. A final manuscript-based study is then presented, which focuses on a methodology for improving alternate mode thermal performance estimates for hybrid solar panels. The conclusion from this study is that the proposed methodology can successfully estimate thermal performance within 5% of actual values. Each of these studies contributes to the project goal of developing a novel solar energy heating system, which can be further developed to reduce global CO2 emissions, and reduce the effects of climate change.


Author(s):  
Jeisell Marisol Cabrera-Chairez ◽  
Néstor Manuel Ortíz-Rodríguez ◽  
Rodrigo Cervando Villegas-Martínez ◽  
Juan Manuel García-González

One of the current problems is the use of energy obtained from fossil fuels, especially due to the emission of greenhouse gases. An option to replace fossil fuels is the use of alternative energies such as solar or wind energy. The objective of this work is to carry out a thermal and energy analysis of an indirect air heating system that receives energy through solar collectors that operate with water as the thermal fluid used in a food dehydration system, in order to know the efficiency of the system and therefore, make improvements to the circuit, in addition to the characterization of the water storage tank of the system, obtain the amount of energy that can be provided and the behavior of temperatures at different operating flows. According to the methodology, the temperature profile was obtained inside the hot water tank in two modes of operation (heating and energy extraction) reaching temperatures of 50 to 70 ° C, where the optimum temperature for drying is found and in turn reaching an efficiency 84%, compared to a conventional drying system that uses LP gas.


2020 ◽  
Vol 2 (1) ◽  
pp. 14
Author(s):  
Brino Ruy Negri ◽  
Marco César Prado Soares ◽  
Antonio Carlos Luz Lisboa ◽  
Julio Roberto Bartoli

One of the main needs of the modern society is the availability of low-cost energy sources, and solar energy arises as an interesting alternative for both the generation of heat and electricity. In this work, a low-cost solar energy reservoir is proposed for domestic water heating. It is comprised of a thermoplastic (polyethylene) water tank thermally insulated by means of two different polymeric coatings: an acrylonitrile butadiene rubber foam, NBR, and a metalized polyester layer. The solar system also contains a flat collector based on a ceiling panel made of poly(vinyl chloride) (PVC) coated with carbon black-filled glaze. The system design is cost effective because all of the parts involved in the solar heating are made from commodity plastic materials. These plastic components present wide commercial availability and are easily handled, so that they can be rapidly assembled to build the entire system. Therefore, the solar heating system is simple, modular, easily scalable, and may be even self-manufactured by the final user. It is an affordable option to the traditional high-cost copper, aluminum and glass solar panels, boilers or tanks used for heat storage.


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.


1994 ◽  
Vol 116 (2) ◽  
pp. 88-93 ◽  
Author(s):  
E. Hahne ◽  
M. Hornberger

At Stuttgart University, a solar heating system for an office building with laboratories and lecture rooms was installed in 1985. It consists of 211 m2 of unglazed solar collectors, a 1050 m3 water-flooded pebble bed heat store, and a heat pump. Heat can be supplied to the store from the solar collectors or from a power station (as waste heat). The whole system has worked successfully for five years under varied strategies. In the first two heating periods, the heating strategy was aimed to collect as much solar energy as possible. Thus, about 60 percent of the heat demand could be covered by solar energy; but the yearly heat pump coefficient of performance (COP) was only around 2.76. With an improved heat pump, a monthly COP of 3.6 was obtained. Heat losses from the storage amounted to about 20 percent.


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.


2019 ◽  
Vol 158 ◽  
pp. 5034-5040
Author(s):  
Di Qin ◽  
Zhun (Jerry) Yu ◽  
Tingting Yang ◽  
Shuishen Li ◽  
Guoqiang Zhang

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