Energy wheel effectiveness: part I—development of dimensionless groups

Simonson, Carey J.; Besant, Robert W.

doi:10.1016/s0017-9310(98)00325-1

Cited by 153 publications

(75 citation statements)

References 6 publications

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“…There is no simple design methodology for a regenerative rotary heat exchanger (Simonson and Besan, 1999). Regenerative rotary heat exchangers are widely used in HVAC systems, though it does not have a simplified design or effectiveness correlation, because they can considerably reduce the heating and cooling loads of a building Shiery and Rengarajan, 1996).…”

Section: Design Methodsmentioning

confidence: 99%

Numerical Modeling of Regenerative Rotary Heat Exchanger: A Review

Baruah¹,

Kumar²

2017

Journal of Biosystems Engineering

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Background: Heat recovery is one of the prominent ways to save a considerable amount of conventional fossil fuel and minimize its adverse effects on the environment. The rotary heat exchanger is one of the most effective and efficient devices for heat recovery or heat exchanging purposes. It is a regenerative type of heat exchanger, which has been studied and used for many heat recovery purposes. However, regenerative thermal wheels have been mostly used as heat recovery systems in buildings. For modeling a rotary regenerator, it is very important to numerically consider all the factors involved, such as effectiveness, rotational speed, geometrical size and shape, and pressure drop (Δp). In recent times, several researchers have actively studied the rotary heat exchangers, both theoretically and experimentally. Reviews: In this paper different advances in the numerical modeling of regenerative rotary heat exchangers in relation to fluid flow and heat transfer have been discussed. Researchers have indicated that the effectiveness of the regenerative rotary heat exchanger depends on various factors including, among many others, rotational speed, rotational period and combustion power. It is reported that with the increase of periodic rotation the deviation of theoretical results from the experimental result increases. The available literature indicates that regenerative heat exchangers are having relatively more effectiveness (60-80%), compared to other heat exchangers. It is also observed that the finite difference method and finite volume methods are mostly used for discretizing the heat transfer governing equations, under some assumptions. Research also indicates that for the effectiveness calculation the ε-NTU method is the most popular and convenient.

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Section: Design Methodsmentioning

confidence: 99%

Numerical Modeling of Regenerative Rotary Heat Exchanger: A Review

Baruah¹,

Kumar²

2017

Journal of Biosystems Engineering

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“…An additional delicate question consists of accurately representing the solid-fluid interface phenomena [11,15]. Nevertheless, advanced mathematical models-including surface diffusion of the adsorbed phase, Knudsen diffusion of the gaseous phase, thermal diffusion and sorption as local processes in the porous desiccant layer-have been adopted to support numerical simulations of the behaviour of desiccant and enthalpy wheels [53][54][55][56].…”

Section: Bimentioning

confidence: 99%

“…The study of the transport phenomena in desiccant airflow systems has been addressed in numerous research works, many of them concerning combined desiccant cooling and dehumidification, air filtering, air dehumidification and energy recovery processes (e.g., [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]). …”

Section: Introductionmentioning

confidence: 99%

On the validity of lumped capacitance approaches for the numerical prediction of heat and mass transfer in desiccant airflow systems

Ruivo

Costa

Figueiredo

2008

International Journal of Thermal Sciences

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In the present work, a detailed model of simultaneous heat and mass transfer through a desiccant micro-porous medium of a channel wall of compact heat and mass exchangers, such as desiccant wheels, was developed. The relevant phenomena considered by this model within the porous medium are surface diffusion of the adsorbed water, Knudsen diffusion of water vapour, heat conduction and the sorption process. A onedimensional formulation of this model is used to investigate the validity of two simplifying approaches based on the lumped-capacitance method. One consists of neglecting the transversal heat and mass transfer resistances within the porous medium, the other of cancelling only the thermal resistance.Results are presented for a wide range of values of the layer thickness of the porous medium. It is concluded that the hypothesis of nullresistances in the cross direction is valid only for layer thicknesses lower than 0.1 mm, approximately, while the approach based on the thermal lumped capacitance model is valid for layer thicknesses lower than 5 mm. Finally, a dimensional analysis of interfacial balances leads to the conclusion that the Biot number for surface diffusion is several orders of magnitude higher than the corresponding thermal Biot number.

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“…Simonson and Besant (7,8) 은 에너지 휠에 대 한 무차원 변수를 유도하였고 수치해석적 방법으로 무 차원 변수가 유용도에 미치는 영향을 분석하여 상관식 을 도출하였다. Zhang and Niu (9,10) 은 제습휠에 대한 유 용도를 회전속도와 NTU에 관하여 분석하였고 수치해 석을 통하여 제습휠 내부의 온도분포와 습도 분포를 분석하였다.…”

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Theoretical Analysis of a Rotary Heat Exchanger Based on a Simplified Model

Son¹,

Kim²,

Lee³

2015

Korean Journal of Air-Conditioning and Refrigeration Engineerin

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A simplified rotary heat-exchanger model was developed with an assumption of a linear temperature distribution along the flow direction. Based on the model, the exact fluid solution and solid temperature variations were obtained and verified from a comparison with previous numerical studies. The heat transfer in the rotary heat exchanger was investigated using the theoretical solutions. The heat exchanger's effectiveness was shown to be saturated, with a rotational-speed increase that is higher than a critical value that is solely dependent on the thermal capacity of the solid matrix but independent of the fluid flow rate; the saturated value of the effectiveness was determined only by the NTU of the heat exchanger. Where the thermal diffusivity of the solid matrix is so slight that the thermal penetration depth becomes smaller than the matrix thickness, the effective thermal capacity of the solid matrix decreased according to the penetration depth. Key words Rotary heat exchanger(회전형 열교환기), Theoretical analysis(이론해석), Effectiveness(유용도), Thermalcapacity(열용량), Thermal diffusivity(열확산계수) †Corresponding author, E-mail: ldy@kist.re.kr

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Energy wheel effectiveness: part I—development of dimensionless groups

Cited by 153 publications

References 6 publications

Numerical Modeling of Regenerative Rotary Heat Exchanger: A Review

Numerical Modeling of Regenerative Rotary Heat Exchanger: A Review

On the validity of lumped capacitance approaches for the numerical prediction of heat and mass transfer in desiccant airflow systems

Theoretical Analysis of a Rotary Heat Exchanger Based on a Simplified Model

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