scholarly journals Numerical Simulation Study for the Performance of a Large Solar Hot Water System With Horizontal Storage Tank

2015 ◽  
Author(s):  
Ru Yang ◽  
Geng-Yi Lin
Keyword(s):  
Numerical Simulation ◽  
System Performance ◽  
Storage Tank ◽  
Large Scale ◽  
Cooling System ◽  
Water System ◽  
Thermal Storage ◽  
Hot Water ◽  
Design Parameters ◽  
Total Load

A large solar hot water system can be utilized to provide driving energy for heating system, heat-driven cooling system, as well as to provide hot water. This research addresses the effects of the storage tank design parameters on the performance of a large-scale solar hot water system with a horizontal storage tank. Most literatures only considered the stratification performance of the thermal storage tank itself instead of considering the overall system performance. Also, there is lack of experimental research data available for the design purpose. Therefore, this study employs a numerical simulation technique to study the design parameters effect of a horizontal thermal storage tank on the performance of a large-scale solar hot water system. In this study, the ANSYS-CFX program is employed to calculate the flow and temperature distributions inside horizontal thermal storage tank. Then the inlets and outlets of the tank are combined with the TRNSYS program to simulate the entire system performance under the weather of three representative cities of Taiwan, (Taipei, Taichung and, Kaohsiung). The results of the present study indicate that the vertical stratification baffles in the tank have important effects on system performance improvement. Quantitative increase of solar fraction of the total load is obtained. The comparison with the system with vertical storage tank is provided. The results of the present study can provide important reference for the large solar hot water system design in improving system efficiency.

Simulation Study for the Performance of a Large Solar Hot Water System Constructed by Natural Circulation Solar DHW System Modules

2012 ◽  
Author(s):  
Ru Yang ◽  
Kuan-Hsiang Yu
Keyword(s):  
Numerical Simulation ◽  
Simulation Study ◽  
System Performance ◽  
Natural Circulation ◽  
Water System ◽  
Hot Water ◽  
Operating Parameters ◽  
Theoretical Support ◽  
System Operating

This research is aimed to study the system performance for a large solar hot water system constructed by connecting a series of small domestic natural-circulation systems. This type of large solar hot water system has been recently installed in Taiwan without either practical or theoretical support. There are few studies on this type of large solar hot water system available. This paper presents the numerical simulation study for the control and the system operating parameters effects on the system performance to provide important information both for users and system designers.

Heat and Mass Transfer Characteristics of a Zeolite 13X/CaCl2 Composite Adsorbent in Adsorption Cooling Systems

2012 ◽  
Author(s):  
K. C. Chan ◽  
Christopher Y. H. Chao ◽  
M. Bahrami
Keyword(s):  
Thermal Conductivity ◽  
Numerical Simulation ◽  
System Performance ◽  
Cooling System ◽  
Design Parameters ◽  
Cooling Power ◽  
Composite Adsorbent ◽  
Zeolite 13X ◽  
Desorption Temperature ◽  
Adsorption Cooling System

The performance of the adsorption cooling system using the zeolite 13X/CaCl2 composite adsorbent was studied using a numerical simulation. The novel zeolite 13X/CaCl2 composite adsorbent with superior adsorption properties was developed in previous studies [11]. It has high equilibrium water uptake of 0.404 g/g between 25°C and 100°C under 870Pa. The system specific cooling power (SCP) and coefficient of performance (COP) were successfully predicted for different operation parameters. The simulated COP with the composite adsorbent is 0.76, which is 81% higher than a system using pure zeolite 13X under desorption temperature of 75°C. The SCP is also increased by 34% to 18.4 W/kg. The actual COP can be up to 0.56 compared to 0.2 for zeolite 13X-water systems, an increase of 180%. It is predicted that an adsorption cooling system using the composite adsorbent could be powered by a low grade thermal energy source, like solar energy or waste heat, using the temperature range of 75°C to 100°C. The performance of the adsorber with different design parameters was also studied in the present numerical simulation. Adsorbents with smaller porosity can have higher thermal conductivity and may result in better system performance. The zeolite bed thickness should be limited to 10mm to reduce the thermal response time of the adsorber. Addition of high thermal conductivity materials, for example carbon nanotube, can also improve the performance of the adsorber. Multi-adsorber tube connected in parallel can be employed to provide large heat transfer surface and maintain a large SCP and COP. The desorption temperature also showed a large effect on the system performance.

scholarly journals A Standard-Based Method to Simulate the Behavior of Thermal Solar Systems with a Stratified Storage Tank

Energies ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 266 ◽  
Author(s):  
Edoardo Alessio Piana ◽  
Benedetta Grassi ◽  
Laurent Socal
Keyword(s):  
Solar System ◽  
Solar Energy ◽  
Storage Tank ◽  
Hot Water ◽  
Design Parameters ◽  
Fluid Temperature ◽  
Forced Circulation ◽  
Solar Systems ◽  
Solar Field ◽  
The Impact

Thermal solar systems are interesting solutions to reduce CO 2 emissions and gradually promote the use of renewable sources. However, sizing such systems and analysing their behavior are still challenging issues, especially for the trade-off between useful solar energy maximization and stagnation risk minimization. The new EPB (Energy Performance of Buildings) standard EN 15316-4-3:2017 offers several methods to evaluate the performance of a forced circulation solar system. One of them is a dynamic hourly method that must be used together with EN 15316-5:2017 for the simulation of the stratified storage tank connected with the solar loop. In this work, such dynamic hourly method is extended to provide more realistic predictions. In particular, modeling of the pump operation due to solar fluid temperature exceeding a set threshold, or due to low temperature differential between solar field and storage tank, is introduced as an on–off control. The implemented code is applied to a case study of solar system for the preparation of domestic hot water and the impact of different design parameters is evaluated. The model predicts a higher risk of overtemperature lock-out or stagnation when the solar field surface is increased, the storage volume is reduced and water consumption is set to zero to simulate summer vacation periods. Finally, a simple modulating control with a time step of a few seconds to a few minutes is introduced, quantitatively showing the resulting benefits in terms of useful solar energy increase, back-up operation savings and reduced auxiliary energy use.

scholarly journals Direct Measurement of Basal Water Pressures: Progress and Problemss

1979 ◽  
Vol 23 (89) ◽  
pp. 309-319 ◽  
Author(s):  
Steven M. Hodge
Keyword(s):  
Large Scale ◽  
Water Pressure ◽  
Water System ◽  
Water Levels ◽  
Hot Water ◽  
Overburden Pressure ◽  
Well Control ◽  
System A ◽  
Pressure Water ◽  
Internal Change

AbstractIn 1975 and 1977, 24 bore holes were drilled to the bed of South Cascade Glacier, Washington, U.S.A., using both electrothermal and hot-water drills. Only two holes connected directly with the basal water system, a significant decrease from the four to five such connections in 13 holes drilled in 1973 and 1974 (Hodge, 1976). Most of the bed, possibly as much as 90%, appears to be hydraulically inactive and isolated from a few active subglacial conduits. Bore holes which penetrate these inactive areas initially should connect eventually with the active basal water system due to bed pressurization by the water standing in the bore hole, provided there is a sufficient supply of water available to form and maintain the connection passageway. These sealed-off areas probably consist of the sub-sole drift and permeability barriers found recently at the bed of Blue Glacier by Engelhardt and others (1978); an increase in the area of bed covered by these features probably caused the decrease in chance of bore-hole connection. This apparently was not due to any external cause but rather was the result of a real internal change in the subglacial hydraulic system which occurred between 1974 and 1975.If most of the area of a glacier bed is hydraulically isolated sub-sole drift, or something similar, such features may well control large-scale glacier sliding changes, since changes in the amount of water having access to the glacier bed will take considerable time to affect the interstitial water pressure in the more widespread sub-sole drift.Water pressures in the active part of the basal water system of South Cascade Glacier are generally in the range of 50–75% of the ice overburden pressure. Water levels in a connected bore hole are probably representative over an area of the bed 100 m or more in extent. A correlation of bore-hole water levels with changes in surface motion supports the idea that the sliding of a temperate glacier is controlled largely by the basal water pressure.

Studies of Fuel-Air Mixture Explosion Characteristics and Structure Fracture and Damage in Large-Scale Metal Oil Storage Tank

2006 ◽  
Vol 324-325 ◽  
pp. 1031-1034
Author(s):  
Yang Du ◽  
Jian Feng Gao ◽  
Xin Sheng Jiang
Keyword(s):  
Numerical Simulation ◽  
Shock Waves ◽  
Storage Tank ◽  
Large Scale ◽  
Simulation Experiment ◽  
Frequent Occurrence ◽  
Oil Storage ◽  
Oil Storage Tank

The fuel-air mixture explosion incidents in the large-scale metal oil storage tank are frequent occurrence and rapidly extend because of the tank structure being fractured and damaged by the fuel-air mixture explosion. In this paper, the simulation experiment and numerical simulation has been carried out for the fuel-air mixture explosion in the large-scale metal storage tank. The shock waves characteristic of the explosive pressure has been studied and discussed. The fracture and damage effects caused by the shock waves characteristic to the tank structure has been analyzed and discussed too.

scholarly journals The Design and Installation of a Combined Concentrating Power Station, Solar Cooling System and Domestic Hot Water System

2015 ◽  
Vol 70 ◽  
pp. 486-494 ◽  
Author(s):  
Jeremy P. Osborne ◽  
Paul Kohlenbach ◽  
Uli Jakob ◽  
Johan Dreyer ◽  
Jamey Kim
Keyword(s):  
Cooling System ◽  
Water System ◽  
Hot Water ◽  
Power Station ◽  
Domestic Hot Water ◽  
Solar Cooling ◽  
Solar Cooling System
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