Multi-dimensional transient heat conduction in heat exchanger tubesheets

Experimental and numerical investigations were carried out to study the effect of weld parameters on the temperature-time history at the back of a tubesheet (adjacent to the gasket) of a shell-and-tube heat exchanger. Experiments were conducted to validate one of the cases simulated (second case in Table 1). The simulated case is called the base case. The predictions obtained for the base case agree well with experimental results. Moreover, parametric studies based on numerical results are carried out for different weld parameters. These parameters include weld duration, weld temperature, tube-sheet size, tubesheet material and sequence of welding. The results indicate that the weld duration has a significant effect on the magnitude of the maximum temperature at the back surface of the tubesheet adjacent to the gasket. Doubling the weld duration increases the maximum temperature by more than 40 per cent. An increase of more than 20 per cent in the peak value of temperature at the back of the tubesheet near the gasket is predicted for five consecutive welds with a time gap of 10 s, whereas a 7.4 per cent increase is predicted for alternate welds.