Dual-circuit chiller with two-pass heat exchanger in a series counterflow arrangement

A dual refrigeration circuit, watercooled chiller has its respective evaporators and condensers interconnected by waterboxes, with each waterbox having an inlet flow and outlet flow connection, and with three passages interconnected with the respective evaporators/condensers of the first and second circuit, and with each of the condensers/evaporators having return bends at their ends to provide a two-pass flow arrangement. The flow in the condenser waterbox passes into a first passage and then in one direction to the condenser of one circuit while the flow into the evaporator waterbox passes into a first passage and then in the opposite direction to one of the circuit evaporators. In this manner, a series counterflow arrangement with two water passes is achieved.