what needs to be verified in deminstions, materials or others if both ST exchangers are used for the same service?
There is a ST heat exchanger that has the same function and design. In that case it is possible. But mostly it is not advisable because tubebundles are design base on process requirements and heat transfer. Second, dimension of tube bundles and its internals is design for a particular shell.
Well, lots of things need to be verified. First, practically speaking, the dimensions must be such that the replacement bundle can fit into the existing shell. Second, look at it from a fluid flow perspective. The dimensions must be such that the the flow will be alterred outside of allowable specifications. The pump in the system will have been sized based on overall pressure drop of the system, so you would need to verify that the drop will not adversely alter performance of the loop or choke the flow. Third, look at the heat transfer issues. The heat transfer is most likely practically independent of the tube material, but it is good practice to verify that the heat conduction of the two tube materials are similar. More important (as in the fluid considerations) is the length and diameter of the flow. The longer the tubes, the more heat will be transferred, and vice versa. The diameter of the tube will affect the amount of heat transferred as well. You would generally want to have the same efficiency of heat removal as the original exchanger. Of course that depends on what is downstream as well. Perhaps you may want to remove more heat? Fourth, from a material perspective, you should ensure that you aren't introducing any reactions into the system. Meaning, don't use anything that will react with whatever you are flowing through the shell or the tube. Also, the adaptation may be tricky from a construction perspective. Just use the tubes that were built for the exchanger. Why is this not an option? Is it old equipment? Why not just fabricate a replacement to specification of the original tubes?
