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Energy Storage and Transport
Published in D. Yogi Goswami, Principles of Solar Engineering, 2023
This mean temperature difference is called the logarithmic mean temperature difference (LMTD). It can be evaluated directly only when the inlet and outlet temperatures of both fluid streams are specified. The use of the LMTD approach is explained in Karlekar and Desmond (1977). The other method is called the effectiveness-NTU method (ε-NTU). The ε-NTU method offers many advantages over the LMTD approach and will be discussed in the following.
Heat Recovery
Published in Neil Petchers, Combined Heating, Cooling & Power Handbook: Technologies & Applications, 2020
There are many types of heat exchangers, although their common function is the transfer of heat from one medium to another. This usually requires both fluids to flow past a separating membrane that provides conductive transfer from the high-temperature fluid to the low-temperature fluid. The rate of heat transfer depends on the logarithmic mean temperature difference, ΔTlmtd, between the fluids.
Detailed evaluation of a heat exchanger in terms of effectiveness and second law
Published in Journal of Turbulence, 2022
Two types of problems are encountered in the analysis of heat exchangers. The first type of problem is the calculation of the dimensions of the heat exchangers. It is quite easy to find the dimensions of the heat exchanger with the logarithmic mean temperature difference (LMTD) method when the mass flow rates and the inlet and outlet temperatures of hot and cold fluids are known or can be deduced from the energy balance. The second type of problem is to find the outlet temperatures of hot and cold fluids in the heat exchanger, heat transfer rate, mass flow rates and inlet temperatures are known. The LMTD method can be used to solve this problem, but it is not useful because it requires many iterations. In 1955, Kays and London developed the e-NTU method, which significantly simplifies the solution of such problems [49].
A practical approach-based technical review on effective utilization of exhaust waste heat from combustion engines
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2023
Rajesh Ravi, Oumaima Douadi, Manoranjitham Ezhilchandran, Mustapha Faqir, Elhachmi Essadiqi, Merouan Belkasmi, Shivaprasad K. Vijayalakshmi
Logarithmic Mean Temperature Difference (LMTD) is a method used to estimate the performance of Hex. In order to determine the total heat transfer, some parameters such as inlet and outlet temperatures, total temperature change and total heat transfer need to be determined (Cai et al. 2019). This method is most useful in estimating the temperature difference when the inlet and outlet and fluid inlet and voltage are known or can be estimated from energy balance Eqs. 3 and 4 (Ravi et al. 2021).
Thermal Modeling and Experimental Validation of Mid-Conductor Winding Cooling
Published in Heat Transfer Engineering, 2023
Ilya T’Jollyn, Jasper Nonneman, Michel De Paepe
With LMTD the logarithmic mean temperature difference, Rtot the total thermal resistance equal to the sum of the conductor, insulation, and convective thermal resistance and Tf,o and Tf,i respectively the outlet and inlet coolant temperature. The temperature difference between inlet and outlet temperature of the cooling fluid is determined by Equation (11).