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5 Ocean Thermal Energy Harvesting
Published in Alireza Khaligh, Omer C. Onar, Energy Harvesting, 2017
To determine the temperature driving force for heat transfer in a heat exchanger, the LMTD is used. It is the logarithmic average of the temperature difference between the hot and cold streams at each end of the exchanger. For countercurrent flow, it is expressed as LMTD=(T1-t2)-(T2-t1)ln((T1-t2)/(T2-t1)).
Thermal Principles Relevant to Equipment and Systems
Published in T. Agami Reddy, Jan F. Kreider, Peter S. Curtiss, Ari Rabl, Heating and Cooling of Buildings, 2016
T. Agami Reddy, Jan F. Kreider, Peter S. Curtiss, Ari Rabl
The LMTD is the logarithmic average temperature difference between the two fluid streams. In simple heat exchangers without the change of phase, it is given by LMTD=ΔT1−ΔT2ln(ΔT1/ΔT2)
The Nuclear Steam Supply System and Reactor Heat Exchangers
Published in Robert E. Masterson, Nuclear Reactor Thermal Hydraulics, 2019
The LMTD is a widely accepted way to calculate the heat flow rate through most heat exchangers. It can be applied to both parallel-flow and counterflow heat exchangers, and the heat flow rate through a single tube in these heat exchangers is given by
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].
Design and Performance Evaluation of a Hydronic Type Compost Heat Exchanger
Published in Cogent Engineering, 2020
Mwewa Chikonkolo Mwape, Isaiah Etemo Muchilwa, Zachary Otara Siagi, Francis D. Yamba
In order to use the LMTD method for determination of the heat exchanger size and design parameters, the outlet and inlet temperatures, mass flowrates (Hot and Cold Fluids), should be known. The process to follow is: Selection of the heat exchanger and its suitability for the application.Using the energy balance to work out the unknown inlet and outlet temperatures and the heat transfer rate.Calculation of the Mean Temperature Difference (MTD) (Tim) and the correction factor F.Overall Heat Transfer Coefficient (U) selection or calculation.Finally calculating the area (A) of the heat exchanger transfer surface.
Experimental investigation on the performance parameters of a helical coil dehumidifier test rig
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2021
Sampath Suranjan Salins, Shahida Anusha Siddiqui, S V Kota Reddy, Shiva Kumar
Logarithmic mean temperature difference (LMTD) is calculated based on the entry and exit temperatures of air and water flowing inside the coil. LMTD is given by the Equation (2).