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# Measurement of Surface Heat Transfer Coefﬁcient

DOI link for Measurement of Surface Heat Transfer Coefﬁcient

Measurement of Surface Heat Transfer Coefﬁcient book

# Measurement of Surface Heat Transfer Coefﬁcient

DOI link for Measurement of Surface Heat Transfer Coefﬁcient

Measurement of Surface Heat Transfer Coefﬁcient book

## ABSTRACT

The surface heat transfer coefﬁcient is used to quantify the rate of convective heat transfer to or from the surface of an object. Convective heat transfer is the mode of energy transfer between a solid surface and the adjacent ﬂuid that is in motion, and it involves the combined effects of conduction and ﬂuid motion. The faster the ﬂuid motion, the greater the convection heat transfer. In the absence of any bulk ﬂuid motion, heat transfer between a solid surface and the adjacent ﬂuid is by pure conduction. The rate of convection heat transfer is observed to be proportional to the temperature difference and is conveniently expressed by Newton’s law of cooling as

Q ¼ hAs(Ts T1) (21:1)

where Q is the net energy added to the system (w) h is the surface or convective heat transfer coefﬁcient (W=m2 K) As is the surface area (m

2) through which convection heat transfer takes place Ts is the surface temperature (K) T1 is the temperature of the ﬂuid (K) sufﬁciently far from the surface

The surface heat transfer coefﬁcient is not a property of a ﬂuid or thematerial. It is an experimentally determined parameter whose value depends on all the variables inﬂuencing convection such as the surface geometry, the nature of ﬂuid motion, the properties of the ﬂuid, and the bulk ﬂuid velocity (Cengel, 2003). In food applications, it is needed to quantify heat transfer during heating or cooling of food materials in ﬂuids. The surface heat transfer coefﬁcient is an important parameter needed in the design and control of food processing equipment where ﬂuids, such as air, nitrogen, steam, water, oil, etc., are used as heating, cooling, frying, freezing, or cooking media (Rahman, 1995).