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Abstarct: Frost accumulation due to moist air flowing on a refrigeration coil cold surface impacts negatively on performance.The frost layer growth has an insulating effect in terms of heat transfer and causes the increase of the air pressuredrop by blocking the free flow area across the coil. In this paper a new modeling approach, accounting for heat and\ mass transfer as well as the hydrodynamics of the problem, is proposed. A related FORTRAN program wasdeveloped, allowing the study of a large range of complex refrigerant circuit configurations. This model predicts thedynamic behavior of a refrigeration coil under dry and frosting conditions. Comparisons were made based on thefrost mass accumulation and pressure drop across the coil and the results were found to agree reasonably well withexperimental results reported in the literature. The model was then applied to study an evaporator typically employedin supermarkets. In terms of refrigerant temperature glide, it was shown that the glide decrease with time because of the decrease of the refrigeration capacity of the coil during the frosting. Further, the air pressure drop is stronglyaffected by the variation of the free flow area.

A Novel Approach to Study the Performance of Finned-Tube

Heat Exchangers under Frosting Conditions

A.L. Bendaoud, M. Ouzzane, Z. Aidoun,and N. Galanis

Journal of Applied Fluid Mechanics, Vol. 4, Special Issue, pp. 9-20, 2011

jafmonline.net/JournalArchive/download?file_ID=15300

Dear Rajesh,

Check this ref.

Heat Exchanger Design Handbook, Second Edition

By Kuppan Thulukkanam

CRC Press – 2013 – 1,260 pages

Series: Mechanical Engineering

Regards!

Azd.

@maddali sir, thanks for the info.

@ Azd, thanks for the info. I will check that out.

Rajesh,

what is HTF and what is geometry of HE?

I use following reference: BSI (1993) BS EN 1048:1993 Heat exchangers – Air cooled liquid coolers ‘dry coolers’ – Test procedure for establishing the performance. British Standard Institution edn, BSI, London

Kind regards,

Ivica

@ Ivica, thanks for the update.

Hi Rajesh

You may use our cloud eTool, [CircS], available at www.refriglab.com, to estimate the circuiting number of evaporator or condenser heat exchanger.

The air coil tube size covers the whole range of current refrigeration and air-conditioning designs from conventional, mini, to micro scale (20mm to 0.1mm ID).

Natural, HFO, and conventional (R290, R600a, R600, R717; R1234yf, R1234ze(e), R1234ze(z); R410a, R407c, R32, R134a, R404a, R22, R12, etc.), 41 refrigerants in total, are available for choosing in the eTool use.

For the new users, if going straight to use [CircS] but having no idea about the Evaporator Inlet or Condenser Outlet Quality for Input, they can use [UnitqS] or [CampS] to obtain it first and then get back to run [CircS].

The interesting question is when/where/how to use this e-Tool? The following are three typical examples from the current users.

1) A household air-conditioner product's refrigerant is planned to change from current R410a to R290 with its capacities being maintained the same. The designer needs to check if the circuiting numbers of current evaporator and condenser air coils are still okay or required to update.

2) An evaporator coil originally designed for a freezer is intended to use for a new cooler so the designer needs to check the circuiting number.

3) For compactness, an air coil's design will be updated with a smaller tube size from current 3/8" to 7mm OD so the designer needs to estimate the circuiting number and see if the required distributor is commercially available or not.