Sulfur Dioxide Solubility in Heat Transfer Oil in the Temperature Range of (293.15 to 313.15) K:  Experimental Results and Related Correlations

An EEPROM (electrically erasable programmable read-only memory) reprogrammable fuse for trimming a digital temperature sensor is designed in a 0.18-µm CMOS EEPROM. The fuse uses EEPROM memory cells, which allow multiple programming cycles by modifying the stored data on the digital trim codes applied to the thermal sensor. By reprogramming the fuse, the temperature sensor can be adjusted with an increased trim variation in order to achieve higher accuracy. Experimental results for the trimmed digital sensor showed a +1.5/−1.0 ℃ inaccuracy in the temperature range of −20 to 125 ℃ for 25 trimmed DTS samples at 1.8 V by one-point calibration. Furthermore, an average mean of 0.40 ℃ and a standard deviation of 0.70 ℃ temperature error were obtained in the same temperature range for power supply voltages from 1.7 to 1.9 V. Thus, the digital sensor exhibits similar performances for the entire power supply range of 1.7 to 3.6 V.

Download Full-text

Study on convective heat transfer correlations for sodium-to-sodium heat exchanger based on STELLA-1 experimental results

Nuclear Engineering and Design ◽

10.1016/j.nucengdes.2020.110963 ◽

2021 ◽

Vol 371 ◽

pp. 110963

Author(s):

Jonggan Hong ◽

Jewhan Lee ◽

Jaehyuk Eoh

Keyword(s):

Heat Transfer ◽

Heat Exchanger ◽

Convective Heat Transfer ◽

Convective Heat ◽

Experimental Results ◽

Heat Transfer Correlations

Download Full-text

Assessment of TiO2 Nanoconcentration and Twin Impingement Jet of Heat Transfer Enhancement—A Statistical Approach Using Response Surface Methodology

Energies ◽

10.3390/en14030595 ◽

2021 ◽

Vol 14 (3) ◽

pp. 595

Author(s):

Mahir Faris Abdullah ◽

Rozli Zulkifli ◽

Hazim Moria ◽

Asmaa Soheil Najm ◽

Zambri Harun ◽

...

Keyword(s):

Heat Transfer ◽

Response Surface Methodology ◽

Response Surface ◽

Heat Transfer Rate ◽

Transfer Rate ◽

Tio2 Nanoparticle ◽

Experimental Results ◽

Improvement Rate ◽

Design Expert ◽

Impingement Jet

Impinging jets are considered to be a well-known technique that offers high local heat transfer rates. No correlation could be established in the literature between the significant parameters and the Nusselt number, and investigation of the interactions between the correlated factors has not been conducted before. An experimental analysis based on the twin impingement jet mechanism was achieved to study the heat transfer rate pertaining to the surface plate. In the current paper, four influential parameters were studied: the spacing between nozzles, velocity, concentration of Nano solution coating and nozzle-plate distance, which are considered to be effective parameters for the thermal conductivity and the heat transfer coefficient of TiO2 nanoparticle, an X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) analysis were done, which highlighted the structure and showed that the nanosolution coated the surface homogenously. Moreover, a comparison was done for the experimental results with that of the predicted responses generated by the Design Expert software, Version 7 User’s Guide, USA. A response surface methodology (RSM) was employed to improve a mathematical model by accounting for a D-optimal design. In addition, the analysis of variance (ANOVA) was employed for testing the significance of the models. The maximum Nu of 91.47, where H = S = 1 cm; Reynolds number of 17,000, and TiO2 nanoparticle concentration of 0.5% M. The highest improvement rate in Nusselt was about 26%, achieved with TiO2 Nanoparticle, when S = 3 cm, H = 6 cm and TiO2 nanoparticle = 0.5 M. Furthermore, based on the statistical analysis, the expected values were found to be in satisfactory agreement with that of the empirical data, which was conducted by accounting for the proposed models’ excellent predictability. Multivariate approaches are very useful for researchers, as well as for applications in industrial processes, as they lead to increased efficiency and reduced costs, so the presented results of this work could encourage the overall uses of multivariate methods in these fields. Hypotheses: A comparison was done for the predicted responses generated by the Design Expert software with the experimental results and then studied to verify the following hypotheses: ► Preparation of three concentrations of TiO2 nanosolution was done and studied. ► The heat transfer rate could be increased by surface coating with TiO2 nanoparticle. ► The heat transfer could be improved by the impingement jet technique with suitable adjustments.

Download Full-text

Influence of Active Cooling at the Trailing Edge on the Thermal Behavior of a Tilting-Pad Journal Bearing

Lubricants ◽

10.3390/lubricants9030026 ◽

2021 ◽

Vol 9 (3) ◽

pp. 26

Author(s):

Nico Buchhorn ◽

Michael Stottrop ◽

Beate Bender

Keyword(s):

Heat Transfer ◽

Thermal Behavior ◽

Experimental Results ◽

Transfer Coefficients ◽

Trailing Edge ◽

Active Cooling ◽

Oil Supply ◽

Tilting Pad ◽

Carry Over ◽

Lower Temperature

In tilting-pad journal bearings (TPJB) with a non-flooded lubrication concept, higher maximum pad temperatures occur than with a flooded bearing design due to the lower convective heat transfer at the pad edges. In this paper, we present an approach to influence the thermal behavior of a five-pad TPJB by active cooling. The aim of this research is to investigate the influence of additional oil supply grooves at the trailing edge of the two loaded pads on the maximum pad temperature of a large TPJB in non-flooded design. We carry out experimental and numerical investigations for a redesigned test bearing. Within the experimental analysis, the reduction in pad temperature is quantified. A simulation model of the bearing is synthesized with respect to the additional oil supply grooves. The simulation results are compared with the experimental data to derive heat transfer coefficients for the pad surfaces. The experimental results indicate a considerable reduction of the maximum pad temperatures. An overall lower temperature level is observed for the rear pad in circumferential direction (pad 4). The authors attribute this effect by a cooling oil carry-over from the previous pad (3). Within the model limits, a good agreement of the simulation and experimental results can be found.

Download Full-text

Thermal Steady States of Gases in a Gravitational Field

Zeitschrift für Naturforschung A ◽

10.1515/zna-2011-1-217 ◽

2011 ◽

Vol 66 (1-2) ◽

pp. 123-133

Author(s):

Kunihiko Kigoshi

Keyword(s):

Heat Transfer ◽

Gravitational Field ◽

Temperature Difference ◽

Thermal Gradient ◽

Vertical Direction ◽

Steady States ◽

Gas Pressure ◽

Experimental Results ◽

Gravity Effect ◽

Gas Molecules

This paper presents results on observations of a temperature difference between the top and bottom of a vessel filled with gas in a gravitational field. The observed temperature at the top of the vessel was always lower than the temperature at the bottom of the vessel, and this temperature difference was persistent and steady over more than 20 h. The magnitude of the temperature difference depends on the types of gas molecules present but is independent of the gas pressure in the vessel within the range from 2.7×104 Pa to 27 Pa. A temperature difference between the top and the bottom is only observed along the vertical direction and is only observed when the vessel contains a gas. These experimental results indicate a gravity effect on molecular heat transfer which enables the transport of energy in the gas without a thermal gradient.

Download Full-text

Evaporation of Single Drops of n-Pentane/n-Hexane Mixtures in Water

Journal of Heat Transfer ◽

10.1115/1.2911908 ◽

1992 ◽

Vol 114 (4) ◽

pp. 965-971 ◽

Cited By ~ 3

Author(s):

H. Shimaoka ◽

Y. H. Mori

Keyword(s):

Heat Transfer ◽

Temperature Difference ◽

Vapor Bubble ◽

Experimental Results ◽

Rise Velocity ◽

Heat Transfer Characteristics ◽

Two Phase ◽

Transfer Characteristics ◽

Preceding Work ◽

Liquid Vapor

The evaporation of isolated drops (2.1−3.0 mm diameter) of nonazeotropic n-pentane/n-hexane mixtures in the medium of water was observed under pressures of 0.11−0.46 MPa and temperature differences up to 27 K. The mole fractions of n-pentane, x, in the mixtures were set at 0.9, 0.5, 0.1, and 0, to be completed by the condition x = 1 set in a preceding work (Shimaoka and Mori, 1990). Experimental results are presented in terms of the instantaneous rise velocity of, and an expression of instantaneous heat transfer to, each drop evaporating and thereby transforming into a liquid/vapor two-phase bubble and finally into a vapor bubble. The dependencies of the heat transfer characteristics on the pressure, the temperature difference, and x are discussed.

Download Full-text