A Sustainable Trigeneration System for Residential Applications

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Azzam Abu-Rayash ◽  
Ibrahim Dincer

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.

Author(s):  
P P Votsis ◽  
S A Tassou ◽  
D R Wilson ◽  
C J Marquand

This paper investigates the performance of a 1.1 m3 stratified hot water storage tank coupled to a vapour compression heat pump system. A comprehensive data acquisition system has been used to obtain the experimental data from a series of static and dynamic tests. In the static experiments a well-defined thermocline has been achieved and the effects of insulation and tank wall thickness on the preservation of the thermocline have been determined. The results indicate that thermal losses in stratified tanks are about 22 per cent higher than the losses in fully mixed tanks. The dynamic experiments have been conducted with an upward-moving thermocline and the major factors influencing its stability have been correlated in terms of the Archimedes number (Gr/Re2). It has been found that good stratification performance can be maintained with Archimedes numbers in the range between 35000 and 55000. A simplified one-dimensional model of the storage tank has been developed and validated against experimental results. The model will be linked to dynamic models of the heat pump and the building to simulate the performance of a heat store/heat pump energy management system.


Author(s):  
Tomas Kropas ◽  
Giedrė Streckienė

Active solar water heating systems typically include hot water storage tanks. The selection of the storage system strongly affects the performance of the entire system. This article presents a detailed analysis of a hot water storage tank during charging and dynamic charging-discharging mode. A numerical model using computational fluid dynamics for the storage tank was developed to investigate the temperature distribution inside of it. Transient thermal analysis was carried using ANSYS Fluent. The numerical model was validated with the experimental results. The energy and exergy analysis as an important tool for the evaluation of the thermal systems quantitatively and qualitatively was performed. The calculation procedures were described. The energy and exergy efficiencies, heat losses were calculated for steady and dynamic processes. Effect of mass flow rate was analysed. The results from parametric analysis showed that charging dynamics reduced the thermocline and efficiency of the hot water storage tank. The dependency of the exergy efficiency of the heat storage tank on the reference environment temperature during the dynamic operation was analysed. Exergy efficiencies for two cities with different climates were compared. This indicated that the higher envi-ronmental temperature gave lower exergy efficiency of the storage tank.


2020 ◽  
Vol 180 ◽  
pp. 107029
Author(s):  
Pin Wu ◽  
Zhichao Wang ◽  
Xiaofeng Li ◽  
Zhaowei Xu ◽  
Yingxia Yang ◽  
...  

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4741
Author(s):  
María Gasque ◽  
Federico Ibáñez ◽  
Pablo González-Altozano

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.


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