Abstract: A one-dimensional transient heat transfer model is developed in this paper for the starting process of printed circuit heat exchangers under large temperature difference. The model considers the internal heat conduction process of the solid material of the printed circuit heat exchanger and is able to predict the temperature behavior of both fluid and solid materials. Transient heat exchanger experiments using N2 as the medium on the printed circuit heat exchanger are conducted. The maximum and minimum temperature of N2 are 450 K and 103 K, respectively. Comparing the model prediction results with the experiment results, the validity of the model is proved for the average deviation of outlet temperature at the cold side during the starting process is 11.7 K and the calculation deviations of heat transfer on both sides are within 7%. Furthermore, the model is applied to calculate and analyze the distribution and variation of the internal temperature of the printed circuit heat exchanger. The results indicate that the heat transfer between the cover plate and the core region of the printed circuit heat exchanger is important and cannot be easily ignored in the simulation of transient process under large temperature difference. The results also show that increasing mass flow rates of heat exchanger mediums and decreasing the thickness of the cover plate are effective methods to shorten the response time of starting process.

Key words: Printed circuit heat exchanger, Starting process, One-dimensional model, Experiment, Heat transfer