Experimental and analytical studies on heat transfer in a scaled intermediate heat exchanger with water

The present paper describes an experimental and analytical study in terms of the temperature distribution and heat transfer of an intermediate heat exchanger (IHX). An experimental apparatus of IHX with the primary heat transport system and the secondary heat transport system is made, and forced and natural circulation experiments are conducted using the apparatus. Temperature distributions inside the shell are measured using the fixed thermocouples as well as traversable thermocouples. The Nusselt numbers are investigated based on the measured temperature distributions. One-dimensional and three-dimensional computations are conducted under the forced circulation and natural circulation conditions in order to simulate the experimental results. One-dimensional computation is conducted during the transient cooling down process using a plant system code for the heat transport systems of primary and secondary loops. For the three-dimensional computations, a quasi-steady state condition is analyzed. Good agreement is obtained between the one-dimensional computational results and the experimental results for both flow patterns. The precise temperature distribution inside the shell is computed by the three-dimensional CFD code. Based on the calculated temperature distribution, the heat transfer coefficients are evaluated and converted into the Nu numbers, and are compared with the experimental results. As a result of the 3D computation, the Nu number levels off to a constant value as the Reynolds number decreases to the laminar flow condition.