The influence of geometrical parameters on the ice formation enhancement in a shell and double coil ice storage system

In the present study, the effect of utilizing two different types of baffles in the channel of the solar air heater is investigated numerically. The studied baffles include angled rectangular baffles and angled V-shaped baffles, which are mounted on the bottom and top walls of the duct, respectively. Both considered baffles were evaluated separately which the studied parameter in each section was the angular position of baffles. Finally, the best-obtained results of both sections were compared to each other. The results indicated that in the rectangular model by comparison between 90°model and no baffle, it was found that the pressure drop and average Nusselt number increase 316.67% and 148.15%, respectively at Reynolds number (Re) = 2000. Also, in V-shaped angled baffles, the thermal efficiency of β = 90°, 60°, 45°, and 30°are 27%, 18%, 13% higher than no baffle channel at Re = 2000, respectively. Furthermore, at low Re (about Re below 300), utilizing baffles into the channel had no effect on the thermal efficiency of the system compared to the no baffle channel. However, at high Re, it was found that the highest thermal efficiency occurred in the model of rectangular baffles with an angle of 90°. K E Y W O R D S baffle, heat-transfer enhancement, numerical simulation, solar air heater

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“…The Friction factor, f , defined as 44 :

f = \frac{2 {normald}_{normalh} Δ P}{ρ {normalu}^{2} B},

where d h and Δ P is hydraulic diameter, pressure drop, respectively. The thermal efficiency of collector is defined by following equation 63‐70 :

η = true(\frac{Nu}{italicN u_{0}} true) {(\frac{f_{0}}{italicf})}^{\frac{1}{3}} .

where Nu 0 and f 0 are defined as Nu and friction factor of the simple channel of the solar air heater without baffles.…”

Section: Mathematical Formulationmentioning

confidence: 99%

Numerical evaluation of the thermal performance of a solar air heater equipped with two different types of baffles

2020

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“…The application of phase change cold energy storage technology in commercial air conditioning systems can effectively reduce the peak load of the power grid. [1] However, in the process of cold energy storage, the charging rate gradually decreases, and the capacity of the refrigeration system decreases continuously. [2] Even if the current refrigeration unit is constantly optimized and the coefficient of performance (COP) of the unit is continuously improved, the problem of efficiency degradation of phase change cold energy storage system cannot be solved.…”

Section: Introductionmentioning

confidence: 99%

High‐Performance Charging Method for Cold Energy Storage Using Foam Freezing

et al. 2021

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Phase change cold energy storage can effectively stabilize the peak value of the power grid, but the cold energy charging rate of phase change material decreases seriously which will reduce the energy efficiency of the system. The cold energy charging performance can be effectively improved by foam freezing, and the foam freezing model is proposed to explore the influence factors and the advantages of this method. Foam freezing is compared with other methods based on the novel concept of cold energy charging coefficient which is carried on the analogy to heat transfer coefficient. It is found that the cold energy charging rate of foam freezing are exponential functions of the height based on e. The foam cold energy charging coefficient is affected by the superposition of convective heat transfer intensity and bubble terminal velocity. The technical path of increasing the cold energy charging coefficient by continuously reducing the bubble size is not feasible. When foam freezing at the radius of 0.6 mm, the cold energy charging coefficient is 237.1 W m−2 K−1, the water equivalent height is 18 mm, and it is the most economical. Foam freezing has advantages over the ice ball and ice‐on‐coil in cold energy charging performance.

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“…Short-length [39], perforated [37], center-cleared [40], alternative axis [41], broken [42] and serrated TTs [43] are some of these modified TTs available in recent works. Also, in addition to using different kinds of insert in a pipe to increase the heat transfer, some researchers utilized various types of heat transfer fluid channel in order to heat transfer augmentation [44][45][46][47][48][49].…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of Non-Uniform Heat Transfer Enhancement in Parabolic Trough Solar Collectors Using Dual Modified Twisted-Tape Inserts

Afsharpanah¹,

Sheshpoli²,

Pakzad³

et al. 2020

Journal of Thermal Engineering

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In this paper, a numerical investigation is presented on heat transfer augmenting by using various kinds of modified multiple twisted tape inserted in solar parabolic trough collectors. The pressurized water is considered as working fluid and Reynolds number varying from 10000 to 20000. The received heat flux on the solar absorber was assumed non-uniform due to hemispheric insolation of sun. The obtained numerical results for the Nusselt number, friction factor and thermal performance are presented for each cases. Various types of twisted tape including single twisted tape, normal, perforated, center-cleared, square, and V-cut dual twisted tape are considered and analyzed. The numerical simulations are performed by a commercial CFD code, ANSYS FLUENT 18.2. The obtained results revealed that at Re=10000 and 20000, the average Nusselt numbers of case with dual v-cut twisted tapes are more than plaine tube by 19.58 and 17.44%, respectively. Moreover, thermal performance of all cases with various twisted tapes is larger than 1 which means that utilizing twisted tape with various configurations leads to more thermal performance than plain tube. The thermal performances of case with dual square-cut twisted tapes (as the best case) for Re=10000 and 20000 are more than plain tube by about 16 and 12% improvement, respectively. Furthermore, for the case with perforated dual twisted tape (as the case with lowest thermal performance), the thermal performances for Re=10000 and 20000 are more than plain tube by about 9.2 and 7% improvement, respectively.

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The influence of geometrical parameters on the ice formation enhancement in a shell and double coil ice storage system

Cited by 31 publications

References 50 publications

Numerical evaluation of the thermal performance of a solar air heater equipped with two different types of baffles

Numerical evaluation of the thermal performance of a solar air heater equipped with two different types of baffles

High‐Performance Charging Method for Cold Energy Storage Using Foam Freezing

Numerical Investigation of Non-Uniform Heat Transfer Enhancement in Parabolic Trough Solar Collectors Using Dual Modified Twisted-Tape Inserts

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