scholarly journals Approximating the solution of the discharging process in a domestic hot water storage tank

2021 ◽  
Vol 27 (1) ◽  
pp. 141-161
Author(s):  
Frank Müller
Keyword(s):  
Storage Tank ◽  
Water Storage ◽  
Hot Water ◽  
Domestic Hot Water ◽  
Water Storage Tank

The Effect of Obstacle Geometry and Position on Thermal Stratification in Solar Hot Water Storage Tanks

2008 ◽  
Author(s):  
Necdet Altuntop ◽  
Veysel Ozceyhan ◽  
Yusuf Tekin ◽  
Sibel Gunes
Keyword(s):  
Storage Tank ◽  
Thermal Stratification ◽  
Water Storage ◽  
Hot Water ◽  
Storage Tanks ◽  
Domestic Hot Water ◽  
Water Storage Tank ◽  
Temperature Distributions ◽  
Solar Powered ◽  
Obstacle Geometry

In this study the effect of obstacle geometry and its position on thermal stratification in solar powered domestic hot water storage tanks are numerically investigated. The goal of this study is to obtain higher thermal stratification and supply hot water for usage as long as possible. The temperature distributions are presented for three different obstacle geometries (1, 2 and 3) and six different distances (f = 0.3, 0.4, 0.5, 0.6, 0.7 and 0.8 mm) from the bottom of the hot water storage tank. The numerical method is validated using both experimental and numerical results available in the literature. It is observed from the results that the thermal stratification increases with the increasing obstacle distance from the bottom of the hot water storage tank for obstacle 1 and 3. The obstacle 2 provides less thermal stratification than the obstacles 1 and 3. As a result, in a duration of 30 minutes, the obstacle 3 provides the best thermal stratification for the distance of f = 0.8 mm from the bottom of the hot water storage tank.

Domestic Hot Water Storage Tank: Design and Analysis for Improving Thermal Stratification

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Nathan Devore ◽  
Henry Yip ◽  
Jinny Rhee
Keyword(s):  
Heat Exchanger ◽  
Storage Tank ◽  
Thermal Stratification ◽  
Reverse Flow ◽  
Storage System ◽  
Water Storage ◽  
Hot Water ◽  
Inlet Temperature ◽  
Domestic Hot Water ◽  
Water Storage Tank

Experimental designs for a solar domestic hot water storage system were built in efforts to maximize thermal stratification within the tank. A stratified thermal store has been shown by prior literature to maximize temperature of the hot water drawn from the tank and simultaneously minimize collector inlet temperature required for effective heat transfer from the solar panels, thereby improving the annual performance of domestic solar hot water heating systems (DSHWH) by 30–60%. Our design incorporates partitions, thermal diodes, and a coiled heat exchanger enclosed in an annulus. The thermal diodes are passive devices that promote natural convection currents of hot water upward, while inhibiting reverse flow and mixing. Several variations of heat exchanger coils, diodes and partitions were simulated using ansys Computational Fluid Dynamics, and benchmarked using experimental data. The results revealed that the optimum design incorporated two partitions separated by a specific distance with four diodes for each partition. In addition, it was discovered that varying the length and diameter of the thermal diodes greatly affected the temperature distribution. The thermal diodes and partitions were used to maintain stratification for long periods of time by facilitating natural convective currents and taking advantage of the buoyancy effect. The results of the experiment and simulations proved that incorporating these elements into the design can greatly improve the thermal performance and temperature stratification of a domestic hot water storage tank.

Domestic Hot Water Storage Tank: Design and Analysis for Improving Thermal Stratification

2012 ◽  
Author(s):  
Nathan Devore ◽  
Henry Yip ◽  
Jinny Rhee
Keyword(s):  
Heat Exchanger ◽  
Storage Tank ◽  
Thermal Stratification ◽  
Reverse Flow ◽  
Storage System ◽  
Water Storage ◽  
Hot Water ◽  
Solar Panels ◽  
Domestic Hot Water ◽  
Water Storage Tank

Experimental designs for a solar domestic hot water storage system were built in efforts to maximize thermal stratification within the tank. A stratified thermal store has been shown by prior literature to maximize temperature of the hot water drawn from the tank while simultaneously increasing the temperature delta required for effective heat transfer from the solar panels, thereby improving the annual performance of domestic solar hot water heating systems (DSHWH) by 30%–60%. Our design incorporates partitions, thermal diodes, and a coiled heat exchanger enclosed in an annulus. The thermal diodes are passive devices that promote natural convection currents of hot water upwards, while inhibiting reverse flow and mixing. Several variations of heat exchanger coils, diodes and partitions were simulated using ANSYS Computational Fluid Dynamics, and benchmarked using experimental data. The results revealed that the optimum design incorporated two partitions separated by a specific distance with four diodes for each partition. In addition, it was discovered that varying the length and diameter of the thermal diodes greatly affected the temperature distribution. The thermal diodes and partitions were used to maintain stratification for long periods of time by facilitating natural convective currents and taking advantage of the buoyancy effect. The results of the experiment and simulations proved that incorporating these elements into the design can greatly improve the thermal performance and temperature stratification of a domestic hot water storage tank.

scholarly journals Minimum Number of Experimental Data for the Thermal Characterization of a Hot Water Storage Tank

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4741
Author(s):  
María Gasque ◽  
Federico Ibáñez ◽  
Pablo González-Altozano
Keyword(s):  
Experimental Data ◽  
Water Temperature ◽  
Temperature Profile ◽  
Storage Tank ◽  
Water Storage ◽  
Hot Water ◽  
Experimental Temperature ◽  
Inlet Temperature ◽  
Water Storage Tank ◽  
Minimum Number

This paper demonstrates that it is possible to characterize the water temperature profile and its temporal trend in a hot water storage tank during the thermal charge process, using a minimum number of thermocouples (TC), with minor differences compared to experimental data. Four experimental tests (two types of inlet and two water flow rates) were conducted in a 950 L capacity tank. For each experimental test (with 12 TC), four models were developed using a decreasing number of TC (7, 4, 3 and 2, respectively). The results of the estimation of water temperature obtained with each of the four models were compared with those of a fifth model performed with 12 TC. All models were tested for constant inlet temperature. Very acceptable results were achieved (RMSE between 0.2065 °C and 0.8706 °C in models with 3 TC). The models were also useful to estimate the water temperature profile and the evolution of thermocline thickness even with only 3 TC (RMSE between 0.00247 °C and 0.00292 °C). A comparison with a CFD model was carried out to complete the study with very small differences between both approaches when applied to the estimation of the instantaneous temperature profile. The proposed methodology has proven to be very effective in estimating several of the temperature-based indices commonly employed to evaluate thermal stratification in water storage tanks, with only two or three experimental temperature data measurements. It can also be used as a complementary tool to other techniques such as the validation of numerical simulations or in cases where only a few experimental temperature values are available.

A Sustainable Trigeneration System for Residential Applications

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Azzam Abu-Rayash ◽  
Ibrahim Dincer
Keyword(s):  
Heat Pump ◽  
Storage Tank ◽  
Renewable Energy Sources ◽  
Water Storage ◽  
Hot Water ◽  
Low Grade ◽  
High Grade ◽  
Pump System ◽  
Water Storage Tank ◽  
Energy And Exergy

Abstract This paper features the integration of two renewable energy sources, making a new trigeneration system for residential applications. The system is primarily powered by solar photovoltaic-thermal (PVT) along with geothermal energy. This trigeneration system consists of a ground source heat pump, solar system, high-grade and low-grade heat exchangers, a heat pump system, and a water storage tank (WST). The objective of this system is to provide the main commodities for residential use including domestic hot water (DHW), electricity, and space heating. The system is analyzed energetically and exergetically using thermodynamic-based concepts. The overall energy and exergy efficiencies of the proposed system are found to be 86.9% and 74.7%, respectively. In addition, the energy and exergy efficiencies of the PVT system are obtained to be 57.91% and 34.19%, respectively. The exergy destructions at the high-grade heat exchanger and the water storage tank add up to 36.9 kW, which makes up 80% of the total exergy destruction of the system. Additionally, parametric studies are conducted to evaluate the degree of impact that various important parameters have on the overall system performance.

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