Heat Transfer During Liquid Contact on Superheated Surfaces

1995 ◽  
Vol 117 (3) ◽  
pp. 693-697 ◽  
Author(s):  
J. C. Chen ◽  
K. K. Hsu
Keyword(s):  
Heat Flux ◽  
Atmospheric Pressure ◽  
Surface Heat Flux ◽  
Temperature Data ◽  
Surface Heat ◽  
Transient Temperature ◽  
Time Varying ◽  
Wall Superheat ◽  
Hot Surface ◽  
Better Than

Several boiling regimes are characterized by intermittent contacts of vapor and liquid at the superheated wall surface. A microthermocouple probe was developed capable of detecting transient surface temperatures with a response time better than 1 ms. The transient temperature data were utilized to determine the time-varying heat flux under liquid contacts. The instantaneous surface heat flux was found to vary by orders of magnitude during the milliseconds of liquid residence at the hot surface. The average heat flux during liquid contact was found to range from 105 to 107 W/m2 for water at atmospheric pressure, as wall superheat was varied from 50 to 450°C.

Comparative Performance of K, E, and J-Type Fast Response Coaxial Probes for Short-Period Transient Measurements

2020 ◽  
Vol 13 (3) ◽  
Author(s):  
Sanjeev Kumar Manjhi ◽  
Rakesh Kumar
Keyword(s):  
Heat Flux ◽  
Surface Heat Flux ◽  
Continuous Wave ◽  
Surface Heat ◽  
Laser Source ◽  
Average Error ◽  
Transient Temperature ◽  
Thermal Coefficient ◽  
Thermal Product ◽  
Short Period

Abstract In many engineering applications, the heating condition changes in a millisecond or less, thus to study such conditions, the coaxial thermocouples (CTs) are used because they have fast responding capability. The present study reveals the construction of K, E, and J-type of coaxial thermocouples and comparative investigation of performance parameters such as determination of thermal coefficient resistance, sensitivity, thermal product (TP), transient temperatures, surface heat flux, response time, and the comparative analysis are performed. These coaxial thermocouples are exposed to four different step heat loads (5 kW/m2, 25 kW/m2, 50 kW/m2, and 70 kW/m2) supplied by a continuous-wave type laser source. Subsequently, the transient temperature histories have been captured for 1.5 s, as well as the thermal product and the surface heat flux are assessed through one-dimensional heat conduction modeling for a semi-infinite body. For the known wattage input heat load, the finite element and analytical study have been done to compare the experimental outcomes. The experimental results have reasonable accuracy with the numerical and analytical results. The average error calculated for transient temperatures and evaluated heat flux are ±0.25% and ±2.5%, and the response times of these coaxial thermocouples are calculated as 40 µs, 36 µs, and 46 µs for K, E, and J-type, respectively, which shows the measuring capability of these CTs for short-duration measurements.

Inverse Heat Flux Problem in Quenching

2000 ◽  
Author(s):  
M. Khairul Alam ◽  
Rex J. Kuriger ◽  
Rong Zhong
Keyword(s):  
Heat Flux ◽  
Heat Conduction ◽  
Surface Heat Flux ◽  
Measurement Errors ◽  
Heat Conduction Problem ◽  
Temperature Data ◽  
Surface Heat ◽  
Measured Temperature ◽  
Inverse Heat Conduction ◽  
Quenching Process

Abstract The quenching process is an important heat treatment method used to improve material properties. However, the heat transfer during quenching is particularly difficult to analyze and predict. To collect temperature data, quench probes have been used in controlled quenching experiments. The process of determination of the heat flux at the surface from the measured temperature data is the Inverse Heat Conduction Problem (IHCP), which is extremely sensitive to measurement errors. This paper reports on an experimental and theoretical study of quenching which is carried out to determine the surface heat flux history during a quenching process by an IHCP algorithm. The inverse heat conduction algorithm is applied to experimental data from a quenching experiment. The surface heat flux is then calculated, and the theoretical curve is compared with experimental results.

MAXIMUM SURFACE HEAT FLUX DURING JET IMPINGEMENT QUENCHING OF VERTICAL HOT SURFACE

2015 ◽  
Vol 22 (3) ◽  
pp. 199-219 ◽  
Author(s):  
C. Agarwal ◽  
Ravi Kumar ◽  
Akhilesh Gupta ◽  
Barun Chatterjee
Keyword(s):  
Heat Flux ◽  
Surface Heat Flux ◽  
Jet Impingement ◽  
Surface Heat ◽  
Maximum Surface ◽  
Hot Surface
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