Abstract: In multistage refrigeration compression, where liquid refrigerant withdraw from a core-in-shell type heat exchanger connected to a high compression stage is passed to a similar exchanger connected to a lower compression stage, liquid level stability in the higher compression stage exchanger is improved by providing an enlarged surge volume. A baffle plate transversing a lower portion of the shell divides the shell into a cooling zone that contains the cores, and a discharge zone that is part of the surge volume. The height of the baffle is selected to facilitate maintenance of at least a minimum functional liquid level in the shell. Liquid refrigerant withdraw from the discharge zone of the high-stage shell is supplied to the cooling zone of a shell connected to a lower compression stage. The liquid level in the shell is maintained by manipulating flow to liquid refrigerant that is flashed into the cooling zone of the higher compression stage shell.