Inclusive analysis and performance evaluation of solar domestic hot water system (a case study)

Ghorab, Mohamed; Entchev, Evgueniy; Yang, Libing

doi:10.1016/j.aej.2017.01.033

Cited by 23 publications

(10 citation statements)

References 20 publications

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“…It is very important to develop more and more precise mathematical models for describing the outlet temperatures of the cold and hot sides of heat exchangers, since these working components are essential in any practical applications, where heat transfer is required between hydraulically separated fluid parts (e.g. in (hydraulic) heating systems like central [1], district [2] or solar heating systems [3,4], etc.). Many modelling approaches like the ones based on the most commonly used [5] effectiveness-number of transfer units (effectiveness-NTU) method [6,7] and the logarithmic mean temperature difference (LMTD) approach [8] assume energy balance between the two sides (that is between the fluids in the two sides) of a heat exchanger without any heat gain/loss to the environment.…”

Section: Introductionmentioning

confidence: 99%

Modified effectiveness and linear regression based models for heat exchangers under heat gain/loss to the environment

2018

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Developing mathematical models for describing heat exchanger outlet temperatures is of great importance for the practice, since heat exchangers are unavoidable elements in any applications, where heat transfer is needed between hydraulically separated fluid parts. The conventional, well-tried physically-based E model (standing for the known effectiveness-NTU approach) is recalled. This model assumes energy balance between the two sides of a heat exchanger (without any interaction with the environment). Based on studies in the literature, mathematical models with similar simplicity and usability to that of the E model, but under heat gain/loss to the environment, are still lacking in the field. This work intends to contribute to filling this gap with two proposed models, called ME and LR models. Based on measured data, all three models are accurate enough for general engineering/modelling purposes, nevertheless, the partly physically-based, partly empirical ME model is more precise than the E model if the heat gain/loss to the environment is considerable, and the empirical (black-box type) LR model is more precise than both the E and ME models if the heat gain/loss is not negligible. Furthermore, the outlet temperatures can be explicitly expressed from the simple linear algebraic relations characterizing all models alike.

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Section: Introductionmentioning

confidence: 99%

Modified effectiveness and linear regression based models for heat exchangers under heat gain/loss to the environment

2018

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“…Lots of research is conducted on solar thermal energy storage systems with renewable sources. M. Ghorab et al [11] verified that the solar fraction, as well as output, would increase proportionally with the increase of the solar collector area.…”

Section: Literature Reviewmentioning

confidence: 98%

“…They used a concentrating solar collector and rockbed storage with air as a working medium for a long-term house heating system. The authors [11] suggested making an energy-efficient house by improving the house design parameters such as walls, insulation, windows, ceiling fan, and so on. Some Universities in Canada are doing some research related to the sessional energy storage systems.…”

Section: Literature Reviewmentioning

confidence: 99%

A Comparison of Solar Photovoltaic and Solar Thermal Collector for Residential Water Heating and Space Heating System

Rahaman¹,

Iqbal²

2019

EJERS

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Almost all single-family detached houses in Canada consume enormous electrical energy for space heating and domestic hot water (DHW) purposes. There are many possibilities to design an energy-efficient house. A solar water heating system can be used for domestic water and space heating. Water temperature can be kept constant always by connecting a heat pump or oil burner to the main tank because solar energy is intermittent. The sizing of solar photovoltaic and collector, tank, heat pump are essential to design an effective system based on the system energy consumption. The existing house is just a conventional house where space and water heating are provided by the grid electricity only. In this research, two possible ways of thermal energy storage systems have been designed for a residential single-family house with solar collector and solar photovoltaic. It is proved that the proposed PV based energy storage system is highly suitable considering lower cost, high output power, flexibility, and easy installation.

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“…Then, another major topic that is not fully developed in the literature is the connection impact of the recirculation loop to the solar tank. SOCOL explains that it can improve the system energy performance as solar production provides a part of the recirculation losses (SOCOL, 2017), which can exceed 35% of the total incoming energy (Ghorab et al, 2017). Previous static model of centralized DHW system with recirculation connection to solar tank has shown a 4% reduction of auxiliary energy consumption for an eight days period (Prapas et al, 1993).…”

Section: Introductionmentioning

confidence: 99%

Influence of mixing valve dynamics and recirculation loop connection to solar tank on large hot water system performances

Becq

Chèze

2021

Solar Energy

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A centralized solar domestic hot water system for a multi-family building is analyzed numerically. The solar preheated water in the solar tank is flowing into an auxiliary tank, connected to a gas boiler. At its output, a mixing device is used to ensure hot water at steady temperature before going through the recirculation loop. This reference system is sized as a typical installation under mild climate in France. The load profile is generated statistically with a one-minute time step. Small time scale phenomena have consequences on the global system behavior: recirculation flow rate variations due to pressure drop change is modeled and validated experimentally. This work's goal is to analyze these effects on two sub-parts of the plant: mixing valve and recirculation loop connection to solar storage. In each case, yearly simulations with 6 seconds time step provide quantitative performance indicators for different sizing and control options. Results show that mixing valve slow response, due to ageing or bad design, leads to a loss of 3.5% energy savings compared to using a fast component. Furthermore, health risks increase as the minimal temperature in the recirculation loop is often under 50°C, which promotes legionella development due to cold water plug flows generated in the loop by the mixing valve dynamic response. The recirculation loop, linked to a solar tank, leads to performance improvement with 6% to 15% increase in energy savings following solar oversizing and reduced overheating risks.

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Inclusive analysis and performance evaluation of solar domestic hot water system (a case study)

Cited by 23 publications

References 20 publications

Modified effectiveness and linear regression based models for heat exchangers under heat gain/loss to the environment

Modified effectiveness and linear regression based models for heat exchangers under heat gain/loss to the environment

A Comparison of Solar Photovoltaic and Solar Thermal Collector for Residential Water Heating and Space Heating System

Influence of mixing valve dynamics and recirculation loop connection to solar tank on large hot water system performances

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