A device for use in a refrigeration or heat pump system. A device includes an outer casing which includes a longitudinal cylindrical shell and end plates arranged at both ends of the shell, and at least three units of the refrigeration or heat pump system arranged inside the same common outer casing, which units are selected from the group consisting of an evaporator, a superheater, an economizer, a condenser, a desuperheater, a sub-cooler and an oil cooler.