Design of Solar Powered Space Heating and Domestic Hot Water System for Libyan Common House

This paper presents thermal performance results of an experimental and numerical simulation study of a solar domestic hot water system (SDHW) for Canadian weather conditions. The experimental test setup includes two solar panels, a solar preheat tank, and an auxiliary propane-fired storage water heater, and an air handler unit for space heating. Experiments were performed on the SDHW system during a different season of the year, over the period March through October 2011 to assess the system performance for different solar gain and water draw schedules. Sunny, partly cloudy and cloudy conditions were explored. The test results were analysed in terms of solar fraction, solar efficiency, and the effects of thermosyphoning and stratification in the solar storage tank. Modelling and simulation of the solar thermal energy system using TRNSYS software was performed. The objective was to optimise key design parameters and to suggest an effective control strategy to maximise the heat extraction from solar collectors. The developed model was based on the experimental test setup. It was first adjusted and verified with the solar gain and water draw schedule experimental data. The results of the numerical simulations were then validated with experimental results obtained with other water draw schedule and weather conditions. Acceptable agreements between the predicted and measured values were obtained at this early stage of development. Further refinements in system and model validation are in progress in order to improve the accuracy of the predictions. Ultimately, as the final product of this investigation, this model will be used to predict the performance of solar domestic hot water and space heating systems in different Canadian locations, different operating conditions and water draw schedules.

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Experimental Comparison of Innovative Composite Sorbents for Space Heating and Domestic Hot Water Storage

Crystals ◽

10.3390/cryst11050476 ◽

2021 ◽

Vol 11 (5) ◽

pp. 476

Author(s):

Vincenza Brancato ◽

Larisa G. Gordeeva ◽

Angela Caprì ◽

Alexandra D. Grekova ◽

Andrea Frazzica

Keyword(s):

Silica Gel ◽

Xrd Analysis ◽

Complete Characterization ◽

Operating Conditions ◽

Hot Water ◽

Experimental Comparison ◽

Space Heating ◽

Calorimetric Analysis ◽

Domestic Hot Water ◽

Composite Sorbents

In this study, the development and comparative characterization of different composite sorbents for thermal energy storage applications is reported. Two different applications were targeted, namely, low-temperature space heating (SH) and domestic hot water (DHW) provision. From a literature analysis, the most promising hygroscopic salts were selected for these conditions, being LiCl for SH and LiBr for DHW. Furthermore, two mesoporous silica gel matrixes and a macroporous vermiculite were acquired to prepare the composites. A complete characterization was performed by investigating the porous structure of the composites before and after impregnation, through N2 physisorption, as well as checking the phase composition of the composites at different temperatures through X-ray powder diffraction (XRD) analysis. Furthermore, sorption equilibrium curves were measured in water vapor atmosphere to evaluate the adsorption capacity of the samples and a detailed calorimetric analysis was carried out to evaluate the reaction evolution under real operating conditions as well as the sorption heat of each sample. The results demonstrated a slower reaction kinetic in the vermiculite-based composites, due to the larger size of salt grains embedded in the pores, while promising volumetric storage densities of 0.7 GJ/m3 and 0.4 GJ/m3 in silica gel-based composites were achieved for SH and DHW applications, respectively.

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Overview of Solutions for the Low-Temperature Operation of Domestic Hot-Water Systems with a Circulation Loop

Energies ◽

10.3390/en14113350 ◽

2021 ◽

Vol 14 (11) ◽

pp. 3350

Author(s):

Theofanis Benakopoulos ◽

William Vergo ◽

Michele Tunzi ◽

Robbe Salenbien ◽

Svend Svendsen

Keyword(s):

Low Temperature ◽

Heat Loss ◽

District Heating ◽

Heating System ◽

Hot Water ◽

Heating Power ◽

Circulation Loop ◽

Space Heating ◽

District Heating System ◽

Domestic Hot Water

The operation of typical domestic hot water (DHW) systems with a storage tank and circulation loop, according to the regulations for hygiene and comfort, results in a significant heat demand at high operating temperatures that leads to high return temperatures to the district heating system. This article presents the potential for the low-temperature operation of new DHW solutions based on energy balance calculations and some tests in real buildings. The main results are three recommended solutions depending on combinations of the following three criteria: district heating supply temperature, relative circulation heat loss due to the use of hot water, and the existence of a low-temperature space heating system. The first solution, based on a heating power limitation in DHW tanks, with a safety functionality, may secure the required DHW temperature at all times, resulting in the limited heating power of the tank, extended reheating periods, and a DH return temperature of below 30 °C. The second solution, based on the redirection of the return flow from the DHW system to the low-temperature space heating system, can cool the return temperature to the level of the space heating system return temperature below 35 °C. The third solution, based on the use of a micro-booster heat pump system, can deliver circulation heat loss and result in a low return temperature below 35 °C. These solutions can help in the transition to low-temperature district heating.

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