# A New method for the estimation of heat transfer coefficient

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## Tarih

1996

## Yazarlar

## Dergi Başlığı

## Dergi ISSN

## Cilt Başlığı

## Yayıncı

Ege Üniversitesi

## Erişim Hakkı

info:eu-repo/semantics/closedAccess

## Özet

SUMMARY Convection heat transfer coefficient was studied in this work. Many applications in industry use convection heat transfer coefficient h. h is often deteraiined experimentally even though it could have been calculated for certain applications from known correlations. Especially, for an original system and/or conditions, ninning experiments is inevitable. One method for the experimental determination of h is known as the classical approach. Due to measurement sensitivities and isolation problems it is not seen practicable. In this work a new approach was studied. New approach can be defined as; One dimensional thin fin model is used to obtain a relation between h and temperature distribution. According to this model we don't have to know the heat transfer rate, we only need the temperature distribution over the fin as accurately as possible. Using this temperature distribution we can calculate h by nonlinear regression. In the study, the new approach was detailed using sensitivity analysis and uncertainty analysis. The aim of the study was not to produce a new correlation for the system. We just wanted to show, the new method can be used for the estimation of convection heat transfer coefficient, more sensitively. Air at different velocities was the test fluid and AISI-304 stainless steel was used as heat conducting material. An electrical resistance was used to supply energy. It was observed that the spacing of temperature measurement sensor played an important role for the result. Theoretically, optimum spacing relation z=mnd was calculated as 1.692. Where m includes h n is the number of sensors and d is the distance between equally spaced sensors. To verify experimentally that z=mnd= 1.692 a number of experiments were performed for different spacings (0.005 m, 0.010 m, 0.015 m, 0.020 m, 0.025 m) and velocities (0.6 iiim/s, 0.8 m/s, 1.1 m/s, 1.4 m/s, 1.9 m/s). It was seen that for small values of velocities the optimum spacing was near 0.01 m but for large values of velocities it is smaller than even 0.005 m. This showed that before the measurements, a proper material with a low thermal conductivity must be chosen. By doing so, since z^mnd, dopt is increased. This also reduces measurement errors in positioning the sensors. IV

## Açıklama

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## Anahtar Kelimeler

Makine Mühendisliği, Mechanical Engineering, Isı geçişi katsayısı, Heat transfer coefficient