Characterization of a Thermosyphon Heat Exchanger for Solar Domestic Hot Water Systems

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
Cynthia A. Cruickshank ◽  
Stephen J. Harrison
Keyword(s):  
Heat Exchanger ◽  
Test Procedure ◽  
Water Systems ◽  
Climatic Conditions ◽  
Hot Water ◽  
Test Method ◽  
Domestic Hot Water ◽  
Operational Conditions ◽  
Flow And Heat Transfer

This paper presents a simplified test method that was developed to allow preconfigured solar domestic hot water systems that use natural convection/thermosyphon heat exchangers to be characterized. The results of this test method produce performance coefficients for simple empirical expressions that describe the fluid flow and heat transfer in the heat-exchange loop. These empirically derived coefficients can be used as an input to a general simulation routine that allows overall system performance to be determined for various loads and climatic conditions. To illustrate the test procedure, results are presented for a typical heat exchanger under a range of operational conditions.

scholarly journals A multipurpose test rig for district heating substations: domestic hot water preparation and keep-warm function comparison

2019 ◽  
Vol 111 ◽  
pp. 06012
Author(s):  
Jad Al Koussa ◽  
Rutger Baeten ◽  
Nico Robeyn ◽  
Robbe Salenbien
Keyword(s):  
Heat Exchanger ◽  
Low Temperature ◽  
District Heating ◽  
Hot Water ◽  
Space Heating ◽  
Test Rig ◽  
Domestic Hot Water ◽  
Heat Demand

A well performing District Heating Substation (DHS) is crucial for the efficiency of the District Heating (DH), especially with the shift towards low temperature 4th generation DH systems. For this reason, testing and characterization of commercially available DHSs becomes important to estimate their effect on the DH network. Within the thermo-technical laboratory of EnergyVille, a multipurpose test rig has been built for testing DHSs. In this setup, different DH conditions and heat demand profiles for space heating and for Domestic Hot Water (DHW) can be emulated. Independent tests have been performed on 4 DHSs from three different manufacturers, focused on the DHW preparation for low DH supply temperature and on the stand-by/keep-warm operation of the substations. The latter maintains a certain temperature within the heat exchanger to avoid delays in the delivery of DHW. The results showed that improvements are needed on DHW production for lower DH supply temperatures. Also, enhancements are needed to reduce losses from the keep-warm function. Given that DH systems can have thousands of substations, this will reduce the overall losses and improve the performance of the DH network.

Three Experimental Techniques to Duplicate the Net Thermal Output of an Irradiated Collector Array

1983 ◽  
Vol 105 (1) ◽  
pp. 92-100 ◽  
Author(s):  
A. H. Fanney ◽  
W. C. Thomas
Keyword(s):  
Heat Source ◽  
Solar Collector ◽  
Water Systems ◽  
Hot Water ◽  
Test Method ◽  
Outdoor Environment ◽  
Experimental Techniques ◽  
Laboratory System ◽  
Domestic Hot Water ◽  
Thermal Output

A relevant and repeatable test method is required to provide a means for rating solar domestic hot water systems. The test method should be independent of the geographical location of the laboratory and the prevailing outdoor environment. Three experimental techniques which reproduce the net thermal output of a normally irradiated solar collector without the use of a solar simulator are investigated. These techniques include the use of an in-line electrical heat source only, use of a nonirradiated collector array in series with a heat source, and the use of electrical strip heaters attached to the back of nonirradiated absorber plates. Two single-tank direct solar domestic hot water systems have been fabricated at the National Bureau of Standards to validate each experimental technique. The solar collector array of one system is subjected to outdoor meteorological conditions. The second system, used to validate the experimental techniques, is located entirely indoors. Daily tests of the solar domestic hot water system with the irradiated collector array were subsequently repeated for the laboratory system using the three experimental techniques. Based on results from several nearly clear and intermittently cloudy days, all three simulation techniques reproduce the net thermal output of the normally irradiated collector array within 4 percent. Pump controller operation can be closely reproduced using two of the techniques. Advantages and limitations of each method are discussed.

Experimental Characterization of a Natural Convection Heat Exchanger for Solar Domestic Hot Water Systems

Solar Energy ◽  
2006 ◽  
Author(s):  
Cynthia A. Cruickshank ◽  
Stephen J. Harrison
Keyword(s):  
Natural Convection ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Computational Models ◽  
Operating Conditions ◽  
Hot Water ◽  
Test Method ◽  
Convection Flow ◽  
Convection Heat ◽  
Domestic Hot Water

To predict the long-term performance of solar domestic hot water (SDHW) systems requires computational models that can characterize the systems under a range of operating conditions. The development of detailed fundamental models that suitably describe the operation of systems with natural convection heat exchangers is, however, difficult and time consuming. The fact that the natural convection flow through the heat exchanger is intrinsically self-controlling and temperature dependent complicates the analysis. One approach to modeling this type of system is to use performance characteristics, empirically derived from experimental data, to predict the performance of the heat exchanger under typical operating conditions. Unfortunately, a significant number of tests may be required to characterize the full operation of the device. This paper presents a simplified test method that was developed to allow pre-configured SDHW systems that use natural convection heat exchangers, to be characterized. The results of this test method produce performance coefficients for simple empirical expressions that describe the fluid flow and heat transfer in the heat-exchange loop. These empirically derived coefficients are an input to a general simulation routine that allows overall system performance to be determined for various loads and climatic conditions. In this paper, data is presented for a typical heat exchanger under a range of operational conditions.

Performance of Solar Domestic Hot Water Systems at the National Bureau of Standards—Measurements and Predictions

1983 ◽  
Vol 105 (3) ◽  
pp. 311-321 ◽  
Author(s):  
A. H. Fanney ◽  
S. A. Klein
Keyword(s):  
Heat Exchanger ◽  
Water System ◽  
Water Systems ◽  
Hot Water ◽  
Time Interval ◽  
National Bureau ◽  
Domestic Hot Water ◽  
Direct System ◽  
System A ◽  
One Year

The thermal performance of six solar domestic hot water systems and a conventional hot water system have been carefully monitored by the National Bureau of Standards in Gaithersburg, Maryland. The system configurations include an evacuated-tube air system with a crossflow heat exchanger and two storage tanks, a single-tank direct system, a double-tank direct system, a single-tank indirect system with a wrap-around heat exchanger, a double-tank indirect system with a coil-in-tank heat exchanger, and a thermosyphon system. Results are presented for a one-year time interval commencing January 1980. This paper includes a detailed description of the hot-water systems, experimental test results, and comparisons with computer predictions using the f-chart method [1].

scholarly journals New Deterministic Mathematical Model for Estimating the Useful Energy Output of a Medium-Sized Solar Domestic Hot Water System

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2753
Author(s):  
Miroslaw Zukowski ◽  
Walery Jezierski
Keyword(s):  
Thermal Power ◽  
Optimization Procedure ◽  
Climatic Conditions ◽  
Point Of View ◽  
Hot Water ◽  
Energy Output ◽  
Daily Consumption ◽  
Software Environment ◽  
Optical Efficiency ◽  
Domestic Hot Water

According to the authors of this paper, the mathematical point of view allows us to see what sometimes cannot be seen from the designer’s point of view. The aim of this study was to estimate the influence of the most important parameters (volume of heat storage tanks, daily consumption of domestic hot water, optical efficiency, heat loss coefficient, and total area of a solar collector) on the thermal power output of solar domestic hot water (SDHW) system in European climatic conditions. Three deterministic mathematical models of these relationships for Madrid, Budapest, and Helsinki were created. The database for the development of these models was carried out using computer simulations made in the TRNSYS software environment. The SDHW system located at the Bialystok University of Technology (Poland) was the source of the measurement results used to validate the simulation model. The mathematical optimization procedure showed that the maximum annual useful energy output that can be obtained from 1 m2 of gross collector area is 1303 kWh in the case of Madrid, 918.5 kWh for Budapest, and 768 kWh for Helsinki weather conditions.

A Design Method for Thermosyphon Solar Domestic Hot Water Systems

1987 ◽  
Vol 109 (2) ◽  
pp. 150-155 ◽  
Author(s):  
M. P. Malkin ◽  
S. A. Klein ◽  
J. A. Duffie ◽  
A. B. Copsey
Keyword(s):  
Flow Rate ◽  
Design Method ◽  
Water Systems ◽  
Hot Water ◽  
Average Flow Rate ◽  
Domestic Hot Water ◽  
Average Flow ◽  
Solar Fraction ◽  
Wide Range ◽  
Flow Circuit

A modification to the f-Chart method has been developed to predict monthly and annual performance of thermosyphon solar domestic hot water systems. Stratification in the storage tank is accounted for through use of a modified collector loss coefficient. The varying flow rate throughout the day and year in a thermosyphon system is accounted for through use of a fixed monthly “equivalent average” flow rate. The “equivalent average” flow rate is that which balances the thermosyphon buoyancy driving force with the frictional losses in the flow circuit on a monthly average basis. Comparison between the annual solar fraction predited by the modified design method and TRNSYS simulations for a wide range of thermosyphon systems shows an RMS error of 2.6 percent.

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