The Experts below are selected from a list of 47229 Experts worldwide ranked by ideXlab platform
Renkun Chen - One of the best experts on this subject based on the ideXlab platform.
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in situ thermal transport measurement of fLowing fluid using modulated photothermal radiometry
International Journal of Heat and Mass Transfer, 2021Co-Authors: Jian Zeng, Ka Man Chung, Sarath Reddy Adapa, Tianshi Feng, Renkun ChenAbstract:Abstract In situ thermal transport measurement of fLowing fluid could be useful for the characterization and diagnosis of practical thermal systems such as fluid heat exchangers and thermal energy storage systems. Despite abundant reports on the ex-situ thermal conductivity measurement of stagnant fluids, a suitable technique for the thermal conductivity measurement of fLowing fluid has been rarely reported. This paper presents the thermal conductivity measurement of fLowing fluid within a pipe using a non-contact modulated photothermal radiometry (MPR) technique, where the surface of the pipe is heated by an intensity-modulated laser and the heat diffuses into the fluid with suitable Modulation Frequency. We design a tube section with small wall thickness suitable for the MPR measurements to maximize the sensitivity of the thermal response to the fluid properties while minimizing the lateral heat spreading effect. Intrinsic thermal conductivity of different fluids was obtained within a proper range of Frequency and fLow velocity where the forced convection effect is negligible. The forced convection effect became prominent at high fLowing velocity and at Low Modulation Frequency, leading to higher effective thermal conductivity of the fluid. It is found that the intrinsic thermal conductivity could be obtained when the fLow velocity is less than 100 mm/sec and ReD1/2Pr1/3 R e D is the Reynolds number and P r is the Prandtl number.
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in situ thermal transport measurement of fLowing fluid using modulated photothermal radiometry
arXiv: Fluid Dynamics, 2021Co-Authors: Jian Zeng, Ka Man Chung, Sarath Reddy Adapa, Tianshi Feng, Renkun ChenAbstract:In situ thermal transport measurement of fLowing fluid could be useful for the characterization and diagnosis of practical thermal systems such as fluid heat exchangers and thermal energy storage systems. Despite abundant reports on the ex-situ thermal conductivity measurement of stagnant fluids, a suitable technique for the thermal conductivity measurement of fLowing fluid has been rarely reported. This paper presents the thermal conductivity measurement of fLowing fluid within a pipe using a non-contact modulated photothermal radiometry (MPR) technique, where the surface of the pipe is heated by an intensity-modulated laser and the heat diffuses into the fluid with suitable Modulation Frequency. We design a tube section with small wall thickness suitable for the MPR measurements to maximize the sensitivity of the thermal response to the fluid properties while minimizing the lateral heat spreading effect. Intrinsic thermal conductivity of different fluids was obtained within a proper range of Frequency and fLow velocity where the forced convection effect is negligible. The forced convection effect became prominent at high fLowing velocity and at Low Modulation Frequency, leading to overestimated thermal conductivity of fluid. It is found that the intrinsic thermal conductivity could be obtained when the fLow velocity is less than 100 mm/sec and ReD1/2Pr1/3 < 100 for DI water and Xceltherm oil under the specified experimental conditions, where Re_D is the Reynolds number and Pr is the Prandtl number.
Jian Zeng - One of the best experts on this subject based on the ideXlab platform.
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in situ thermal transport measurement of fLowing fluid using modulated photothermal radiometry
International Journal of Heat and Mass Transfer, 2021Co-Authors: Jian Zeng, Ka Man Chung, Sarath Reddy Adapa, Tianshi Feng, Renkun ChenAbstract:Abstract In situ thermal transport measurement of fLowing fluid could be useful for the characterization and diagnosis of practical thermal systems such as fluid heat exchangers and thermal energy storage systems. Despite abundant reports on the ex-situ thermal conductivity measurement of stagnant fluids, a suitable technique for the thermal conductivity measurement of fLowing fluid has been rarely reported. This paper presents the thermal conductivity measurement of fLowing fluid within a pipe using a non-contact modulated photothermal radiometry (MPR) technique, where the surface of the pipe is heated by an intensity-modulated laser and the heat diffuses into the fluid with suitable Modulation Frequency. We design a tube section with small wall thickness suitable for the MPR measurements to maximize the sensitivity of the thermal response to the fluid properties while minimizing the lateral heat spreading effect. Intrinsic thermal conductivity of different fluids was obtained within a proper range of Frequency and fLow velocity where the forced convection effect is negligible. The forced convection effect became prominent at high fLowing velocity and at Low Modulation Frequency, leading to higher effective thermal conductivity of the fluid. It is found that the intrinsic thermal conductivity could be obtained when the fLow velocity is less than 100 mm/sec and ReD1/2Pr1/3 R e D is the Reynolds number and P r is the Prandtl number.
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in situ thermal transport measurement of fLowing fluid using modulated photothermal radiometry
arXiv: Fluid Dynamics, 2021Co-Authors: Jian Zeng, Ka Man Chung, Sarath Reddy Adapa, Tianshi Feng, Renkun ChenAbstract:In situ thermal transport measurement of fLowing fluid could be useful for the characterization and diagnosis of practical thermal systems such as fluid heat exchangers and thermal energy storage systems. Despite abundant reports on the ex-situ thermal conductivity measurement of stagnant fluids, a suitable technique for the thermal conductivity measurement of fLowing fluid has been rarely reported. This paper presents the thermal conductivity measurement of fLowing fluid within a pipe using a non-contact modulated photothermal radiometry (MPR) technique, where the surface of the pipe is heated by an intensity-modulated laser and the heat diffuses into the fluid with suitable Modulation Frequency. We design a tube section with small wall thickness suitable for the MPR measurements to maximize the sensitivity of the thermal response to the fluid properties while minimizing the lateral heat spreading effect. Intrinsic thermal conductivity of different fluids was obtained within a proper range of Frequency and fLow velocity where the forced convection effect is negligible. The forced convection effect became prominent at high fLowing velocity and at Low Modulation Frequency, leading to overestimated thermal conductivity of fluid. It is found that the intrinsic thermal conductivity could be obtained when the fLow velocity is less than 100 mm/sec and ReD1/2Pr1/3 < 100 for DI water and Xceltherm oil under the specified experimental conditions, where Re_D is the Reynolds number and Pr is the Prandtl number.
K W E Cheng - One of the best experts on this subject based on the ideXlab platform.
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a cascaded multilevel inverter based on switched capacitor for high Frequency ac power distribution system
IEEE Transactions on Power Electronics, 2014Co-Authors: Junfeng Liu, K W E ChengAbstract:The increase of transmission Frequency reveals more merits than Low- or medium-Frequency distribution among different kinds of power applications. High-Frequency inverter serves as source side in high-Frequency ac (HFAC) power distribution system (PDS). However, it is complicated to obtain a high-Frequency inverter with both simple circuit topology and straightforward Modulation strategy. A novel switched-capacitor-based cascaded multilevel inverter is proposed in this paper, which is constructed by a switched-capacitor frontend and H-Bridge backend. Through the conversion of series and parallel connections, the switched-capacitor frontend increases the number of voltage levels. The output harmonics and the component counter can be significantly reduced by the increasing number of voltage levels. A symmetrical triangular waveform Modulation is proposed with a simple analog implementation and Low Modulation Frequency comparing with traditional multicarrier Modulation. The circuit topology, symmetrical Modulation, operation cycles, Fourier analysis, parameter determination, and topology enhancement are examined. An experimental prototype with a rated output Frequency of 25 kHz is implemented to compare with simulation results. The experimental results agreed very well with the simulation that confirms the feasibility of proposed multilevel inverter.
Tianshi Feng - One of the best experts on this subject based on the ideXlab platform.
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in situ thermal transport measurement of fLowing fluid using modulated photothermal radiometry
International Journal of Heat and Mass Transfer, 2021Co-Authors: Jian Zeng, Ka Man Chung, Sarath Reddy Adapa, Tianshi Feng, Renkun ChenAbstract:Abstract In situ thermal transport measurement of fLowing fluid could be useful for the characterization and diagnosis of practical thermal systems such as fluid heat exchangers and thermal energy storage systems. Despite abundant reports on the ex-situ thermal conductivity measurement of stagnant fluids, a suitable technique for the thermal conductivity measurement of fLowing fluid has been rarely reported. This paper presents the thermal conductivity measurement of fLowing fluid within a pipe using a non-contact modulated photothermal radiometry (MPR) technique, where the surface of the pipe is heated by an intensity-modulated laser and the heat diffuses into the fluid with suitable Modulation Frequency. We design a tube section with small wall thickness suitable for the MPR measurements to maximize the sensitivity of the thermal response to the fluid properties while minimizing the lateral heat spreading effect. Intrinsic thermal conductivity of different fluids was obtained within a proper range of Frequency and fLow velocity where the forced convection effect is negligible. The forced convection effect became prominent at high fLowing velocity and at Low Modulation Frequency, leading to higher effective thermal conductivity of the fluid. It is found that the intrinsic thermal conductivity could be obtained when the fLow velocity is less than 100 mm/sec and ReD1/2Pr1/3 R e D is the Reynolds number and P r is the Prandtl number.
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in situ thermal transport measurement of fLowing fluid using modulated photothermal radiometry
arXiv: Fluid Dynamics, 2021Co-Authors: Jian Zeng, Ka Man Chung, Sarath Reddy Adapa, Tianshi Feng, Renkun ChenAbstract:In situ thermal transport measurement of fLowing fluid could be useful for the characterization and diagnosis of practical thermal systems such as fluid heat exchangers and thermal energy storage systems. Despite abundant reports on the ex-situ thermal conductivity measurement of stagnant fluids, a suitable technique for the thermal conductivity measurement of fLowing fluid has been rarely reported. This paper presents the thermal conductivity measurement of fLowing fluid within a pipe using a non-contact modulated photothermal radiometry (MPR) technique, where the surface of the pipe is heated by an intensity-modulated laser and the heat diffuses into the fluid with suitable Modulation Frequency. We design a tube section with small wall thickness suitable for the MPR measurements to maximize the sensitivity of the thermal response to the fluid properties while minimizing the lateral heat spreading effect. Intrinsic thermal conductivity of different fluids was obtained within a proper range of Frequency and fLow velocity where the forced convection effect is negligible. The forced convection effect became prominent at high fLowing velocity and at Low Modulation Frequency, leading to overestimated thermal conductivity of fluid. It is found that the intrinsic thermal conductivity could be obtained when the fLow velocity is less than 100 mm/sec and ReD1/2Pr1/3 < 100 for DI water and Xceltherm oil under the specified experimental conditions, where Re_D is the Reynolds number and Pr is the Prandtl number.
Sarath Reddy Adapa - One of the best experts on this subject based on the ideXlab platform.
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in situ thermal transport measurement of fLowing fluid using modulated photothermal radiometry
International Journal of Heat and Mass Transfer, 2021Co-Authors: Jian Zeng, Ka Man Chung, Sarath Reddy Adapa, Tianshi Feng, Renkun ChenAbstract:Abstract In situ thermal transport measurement of fLowing fluid could be useful for the characterization and diagnosis of practical thermal systems such as fluid heat exchangers and thermal energy storage systems. Despite abundant reports on the ex-situ thermal conductivity measurement of stagnant fluids, a suitable technique for the thermal conductivity measurement of fLowing fluid has been rarely reported. This paper presents the thermal conductivity measurement of fLowing fluid within a pipe using a non-contact modulated photothermal radiometry (MPR) technique, where the surface of the pipe is heated by an intensity-modulated laser and the heat diffuses into the fluid with suitable Modulation Frequency. We design a tube section with small wall thickness suitable for the MPR measurements to maximize the sensitivity of the thermal response to the fluid properties while minimizing the lateral heat spreading effect. Intrinsic thermal conductivity of different fluids was obtained within a proper range of Frequency and fLow velocity where the forced convection effect is negligible. The forced convection effect became prominent at high fLowing velocity and at Low Modulation Frequency, leading to higher effective thermal conductivity of the fluid. It is found that the intrinsic thermal conductivity could be obtained when the fLow velocity is less than 100 mm/sec and ReD1/2Pr1/3 R e D is the Reynolds number and P r is the Prandtl number.
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in situ thermal transport measurement of fLowing fluid using modulated photothermal radiometry
arXiv: Fluid Dynamics, 2021Co-Authors: Jian Zeng, Ka Man Chung, Sarath Reddy Adapa, Tianshi Feng, Renkun ChenAbstract:In situ thermal transport measurement of fLowing fluid could be useful for the characterization and diagnosis of practical thermal systems such as fluid heat exchangers and thermal energy storage systems. Despite abundant reports on the ex-situ thermal conductivity measurement of stagnant fluids, a suitable technique for the thermal conductivity measurement of fLowing fluid has been rarely reported. This paper presents the thermal conductivity measurement of fLowing fluid within a pipe using a non-contact modulated photothermal radiometry (MPR) technique, where the surface of the pipe is heated by an intensity-modulated laser and the heat diffuses into the fluid with suitable Modulation Frequency. We design a tube section with small wall thickness suitable for the MPR measurements to maximize the sensitivity of the thermal response to the fluid properties while minimizing the lateral heat spreading effect. Intrinsic thermal conductivity of different fluids was obtained within a proper range of Frequency and fLow velocity where the forced convection effect is negligible. The forced convection effect became prominent at high fLowing velocity and at Low Modulation Frequency, leading to overestimated thermal conductivity of fluid. It is found that the intrinsic thermal conductivity could be obtained when the fLow velocity is less than 100 mm/sec and ReD1/2Pr1/3 < 100 for DI water and Xceltherm oil under the specified experimental conditions, where Re_D is the Reynolds number and Pr is the Prandtl number.
