Improvement of collection efficiency and solar fraction in solar thermal storage system using a 3-way valve and a 2-stage flowrate control

Kim, Jong Hyun; Lee, Uk Jae; Li, LongJie; Kim, Chul; Hong, Hyun Pyo

doi:10.1007/s12206-016-0644-1

Cited by 4 publications

(2 citation statements)

References 11 publications

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“…To maintain a constant temperature of the cooling water supplied to the cooler of each part of the ship, waste heat is discharged by installing a three-way valve and a controller in the central cooling water cooler and by adjusting the opening of the three-way valve according to the cooling water temperature on the outlet side of the three-way valve [8]. A three-way valve is adopted as a remedy of the temperature reversal in the water storage tank and a two-stage flowrate is implemented as the flowrate control strategy [9].…”

Section: Introduction 1backgroundmentioning

confidence: 99%

Design of Energy Saving Controllers for Central Cooling Water Systems

Lee

Jeon²,

Jung

et al. 2021

JMSE

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Since fuel prices account for approximately 40% of a ship’s operating costs, shipping companies worldwide have made significant efforts to save energy on board such as introducing new technologies or machine operation methods. Many ship operators have adopted an advanced control system using a variable-speed pump and/or an optimizing control system of a three-way valve on the outlet side of the central cooling system. It is often considered that the best way to control a central cooling system is to integrate the two control systems. However, when applied in practice, there is a frequent uncontrollable phenomenon in which the three-way valve is opened to its minimum and the variable-speed seawater pump is operated at its maximum, resulting in a large amount of energy consumption. Therefore, in this study, the speed of the variable-speed seawater pump is set to the minimum, and the feed-forward controller is adopted for the three-way valve control system. The input variable of the feed-forward controller is the Main Engine load, and it is designed to directly control the bypass openness with the three-way valve controller. Using this design, it was demonstrated that the variable-speed seawater pump was operated at a minimum and energy was saved.

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Section: Introduction 1backgroundmentioning

confidence: 99%

Design of Energy Saving Controllers for Central Cooling Water Systems

Lee

Jeon²,

Jung

et al. 2021

JMSE

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“…Since the solar collector and water tank are the key components that procure energy savings in a SDHW system, the possible causes of reduced overall system performance in real dynamic operation were previously tracked in priority to these components rather than to heat distribution circuit. Indeed, it has been shown that preserving stratification inside the water tank improves the energy recovery from the solar loop (Kim et al, 2016). For these reasons tank stratification has been extensively studied and modeled in addition to developing different technical solutions to address this issue, for instance the water snake (Al-Habaibeh et al, 2018) or horizontal obstacles inside the water tank (Altuntop et al, 2005).…”

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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One-dimensional modelling of sensible heat storage tanks with immersed helical coil heat exchangers: A critical review

Langerova,

Matuska

2023

Journal of Energy Storage

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Improvement of collection efficiency and solar fraction in solar thermal storage system using a 3-way valve and a 2-stage flowrate control

Cited by 4 publications

References 11 publications

Design of Energy Saving Controllers for Central Cooling Water Systems

Design of Energy Saving Controllers for Central Cooling Water Systems

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

One-dimensional modelling of sensible heat storage tanks with immersed helical coil heat exchangers: A critical review

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