Heat transfer coefficient: a review of measurement techniques

Abstract

Heat transfer coefficient is a basic parameter used in the calculation of convective heat transfer problems. Due to the importance of the experimental measurements for the development of convective heat transfer, this review identifies, classifies and describes the experimental methods used for the measurement of heat transfer coefficient. The methods were classified into five major groups: (1) direct method, (2) transient method, (3) Wilson method, (4) heat/momentum/mass transfer analogy method and (5) boundary layer thickness method. Their applications, limitations and the reported accuracy were evaluated in the context of new developments in temperature and heat flux measurement techniques. Finally, this review provides criteria for the selection of the most suitable technique for measurements of heat transfer coefficient according to the aspects of spatial resolution, geometric scale, intrusiveness, fluid type, response time and accuracy. Keywords Heat transfer coefficient • Temperature • Heat flux • Convection • Experimental measurements List of symbols 1D One-dimensional 2D Two-dimensional A Surface area (m 2) A e Outer tube surface area (m 2) A i Inner tube surface area (m 2) A s Surface area (m 2) C e Thermal resistances outside the tube and the tube wall (K/W) (constant) C i Constant C f Fanning friction factor (-), C f = s V 2 ∕2 c Constant (-) c p Specific heat capacity (J/kg K) c p,i Specific heat capacity at constant pressure (J/ kg K) d Diameter (m) d e Outer tube diameter (m) d i Inner tube diameter (m) D m Mass diffusivity (m 2 /s) f Darcy friction factor (-), f = 4 ⋅ C f * Cristiano Bigonha Tibiriçá

Research methods in the study of heat transfer coefficient during flow in minichannels

“…According to the Newton's law of cooling, heat transfer coefficient of investigated heat exchanger is defined as [15]:…”

“…Over the years the Wilson plot method has undergo series of modifications in order to extend its application to more sophisticated heat exchanger design and enhanced flow conditions. More detailed information concerning the application of both the original and modified Wilson plot method in various heat transfer problems can be found in literature [10][11][12][13][14][15] The aim of the paper is to present the available research methods widely applied in the investigations of heat transfer coefficient in minichannels. The main focus was put on thermal balance method and mass transfer method.…”

Numerical Simulation and Experimental Research on the Quenching Process of 1045 Steel Based on Thermo–Fluid–Solid Coupling Model

“…[3] Scholars mainly optimize the heat transfer coefficient from two aspects: measurement methods and measurement tools. [4,5] However, the heat transfer coefficient is influenced by many factors, such as the quenching medium type, [6] surface condition, [7] surface shape, [8] and stirring intensity. [9] Thus, the required heat transfer coefficient for different quenching process simulations is also different, which results in the need for an enormous database of heat transfer coefficients to accommodate different quenching processes.…”

Determination of the heat transfer coefficient between pellets and air during the modernization of a pelletizing tower based on industrial research

“…Refinement of methods for calculating heat transfer coefficients using experimental data in various equipment is a task to which many scientific works of scientists in different countries of the world are devoted [3][4][5][6][7][8][9][10]. But specifying the methods of calculating these coefficients for systems of drops or pellets and air, in their mutual movement, is a difficult task, the number of publications in this direction is limited, and similar studies are relevant.…”