Kaltra - Brazed Aluminium Microchannel Evaporators

Microchannel heat exchangers adopted for evaporator and heat pump applications

In microchannel evaporators, an internal refrigerant distributor is used in combination with vertical microchannel tube orientation and oversized manifolds. This provides optimum thermal performance over a wide range of operating conditions and design issues, ensures uniform refrigerant distribution in the inlet manifold and equal refrigerant injection across all the multi-port microchannel tubes, and counteracts the effects of outlet manifold pressure drop.

Refrigerant distributor of the microchannel evaporator can be operated in reverse refrigerant flow for heating duty in the heat pumps and by using switching valves that allow the same microchannel evaporator to then be used as a condenser for heating operation.

The new generation microchannel evaporator significantly differs from other types in many ways, including the following features:

• Liquid/gas separation of fluid delivered to the distributor

• Weir arrangement to facilitate refrigerant injection into the orifices

• Directional control of the refrigerant flow to the inlet manifold and to the multiport microchannel tubes

• Secondary openings to create a pressure drop to spread out the refrigerant evenly across the length of the manifold

• Ternary openings to inject refrigerant into the tube chambers

• Isolation of each microchannel tube as secondary chambers to prevent refrigerant flow between the microchannel tubes

• Special surface geometry for capturing and holding refrigerant to feed microchannel tubes

• Evaporator design permits refrigerant to flow in both directions for use in reversible heat pumps