Search results for "heat exchange"

Prediction of Swirling Flow in a Corrugated Channel

1991

Laminar and turbulent flow in a corrugated channel is simulated using HARWELL-FLOW3D. The channel represents a typical cell within a proposed design for the heat-transfer element of a rotary regenerator. Velocity vectors in planes perpendicular and parallel to the axis of a corrugation are visualised using Harwell’s graphics package, OUTPROC. Both programs were mn on Harwell’s Cray 2. The velocity vector plots show clear evidence of swirl, which is thought to be the mechanism responsible for the high rates of heat transfer in this type of heat-exchanger geometry. The swirl strength is shown to be a function of the channel geometry.

The calculation of the mean radiant temperature of a subject exposed to the solar radiation – A generalised algorithm

2005

Abstract The thermal sensation experienced by a subject in a confined environment is significantly affected by the radiative heat exchange between the human body and the surrounding surfaces: it contributes as far as 30% of the whole thermal exchanges of the subject. Besides, the presence of high-intensity radiation sources like, for example, the sun, may appreciably modify the radiant field to which people are exposed. As a consequence, this could alter notably the comfort conditions. In order of properly taking into account this issue, a simple analytical method is introduced in this work, that allows the easy evaluation of the thermal radiant field induced by the presence of the solar ra…

A Numerical Approach to Study Shell-Side Fluid Flow in Shell-and-Tube Heat Exchangers

2022

Abstract The detailed CFD simulation of the shell-side flow inside shell-and-tube heat exchangers results prohibitive for large-size components, due to the large number of tubes, together with the multi-scale nature of the flow features. To overcome this issue, the porous media approach can be adopted, substituting the tube bundle with a porous domain, where a suitable momentum sink term in the Navier-Stokes equation is provided. In this paper, a novel numerical approach to estimate the crossflow shell-side pressure drop is presented: a complete characterization of the tube bundle was performed by running 2D-CFD steady-state isothermal analyses, collecting pressure gradient magnitudes and d…

Large-Eddy Simulation of Flow and Heat Transfer in Compact Heat Exchangers

1994

LES results are presented for different heat exchanger geometries. Subgrid terms were usually computed by the Smagorinsky model; preliminary comparative results are also given for the ‘dynamic’ subgrid model. The numerical methods used were those implemented in a commercial general-purpose code (CFDS-FLOW3D); they included a finite-volume approach, colocated body-fitted grids, central differencing for the advection terms, the SIMPLEC algorithm, and Crank-Nicolson time stepping. Predictions arc compared with experimental measurements (including local Nu distributions), and with results from a low-Reynolds number k-e model. In most cases, LES was more ‘robust’ and required little more CPU tim…

Flow and Heat Transfer in Corrugated Passages: Direct and Large Eddy Simulation and Comparison with Experimental Results

1993

Direct and large-eddy numerical simulations are presented for the transitional and turbulent flow with heat transfer in corrugated passages, representative of compact heat exchangers such as rotary air preheaters (regenerators), at Reynolds number ranging from 103 to 104. Pressure drop and heat transfer results are compared with wind-tunnel experimental data; the agreement is quite satisfactory, and superior to that obtained by more traditional methods.

Numerical prediction of turbulent flow and heat transfer in helically coiled pipes

2010

Abstract Computational results were obtained for turbulent flow and heat transfer in curved pipes, representative of helically coiled heat exchangers. Following a grid refinement study, grid independent predictions from alternative turbulence models ( k – ɛ , SST k – ω and RSM– ω ) were compared with DNS results and experimental pressure drop and heat transfer data. Using the SST k – ω and RSM– ω models, pressure drop results were in excellent agreement with literature data and the Ito correlation. For heat transfer, the literature is not comparably complete or accurate, but a satisfactory agreement was obtained in the range of available data. Unsatisfactory results, both for pressure drop …

Flow and Heat Transfer Predictions in Flow Passages of Air Preheaters: Assessment of Alternative Modelling Approaches

1997

Investigation of Flow and Heat Transfer in Corrugated Passages – II. Numerical Simulations

1996

Investigation of Flow and Heat Transfer in Corrugated Passages – I. Experimental Results

1996

Experimental results on a solar desiccant and evaporative cooling system equipped with wet heat exchangers

2012

An innovative solar assisted desiccant and evaporative cooling (DEC) system for building air conditioning has been installed at the Solar Laboratory of the University of Palermo. In this system, air-to-air packaged wet heat exchangers are used to maximise the exploitation of the evaporative cooling potential associated with the exhaust air stream. Results obtained are very positive, showing that DEC systems can benefit from the use of wet heat exchangers to efficiently cool the air stream after the adsorption process in the desiccant wheel, without any change in moisture content