Plate-type heat pump air conditioner heat exchanger for a unitary heat pump air conditioner

A unitary heat pump air conditioner (Unitary HPAC), comprising:

• a plate-type HPAC heat exchanger having a plurality of plates stacked and hermetically sealed between an upstream end plate and a downstream end plate, defining:
• a first heat exchanger portion configured to receive a refrigerant flow and a hot side coolant flow having a lower temperature than the refrigerant flow, wherein said refrigerant flow is in non-contact thermal communication with the hot side coolant flow, whereby heat energy is transferred from the refrigerant flow to the hot side coolant flow;
• and
• a second heat exchanger portion is configured to receive a refrigerant flow exiting from said first heat exchanger portion and a cold side coolant flow having a higher temperature than the refrigerant flow exiting from said first heat exchanger portion, wherein the cold side coolant flow is in non-contact thermal communication with the refrigerant flow, whereby heat energy is transferred from the cold side coolant flow to the refrigerant flow;
• wherein said first heat exchanger portion comprises:
• a hot side coolant inlet, a hot side coolant outlet, and a high pressure refrigerant inlet disposed on said upstream end plate,
• a hot side coolant passageway in fluid communication with said hot side coolant inlet and hot side coolant outlet;
• a first boundary plate spaced from said upstream end plate defining a high pressure refrigerant port;
• and
• a high pressure refrigerant passageway in fluid communication with said refrigerant inlet of said upstream plate and said high pressure refrigerant port of first boundary plate;
• wherein said hot side coolant passageway and said high pressure refrigerant passageway are in non-contact thermal communication;
• wherein said second heat exchanger portion comprises:
• a cold side coolant inlet, a cold side coolant outlet, and a low pressure refrigerant outlet disposed on said downstream end plate,
• a cold side coolant passageway in fluid communication with said cold side coolant inlet and cold side coolant outlet;
• an elongated refrigerant expansion chamber extending in a direction toward said downstream end plate;
• and
• a low pressure refrigerant passageway in fluid communication with said refrigerant expansion chamber and said low pressure refrigerant outlet;
• wherein said cold side coolant passageway and said low pressure refrigerant passageway are in non-contact thermal communication;
• and
• wherein said second heat exchanger portion further comprises a second boundary plate defining a low pressure refrigerant port spaced from said downstream end plate, wherein said low pressure refrigerant passageway extends from said refrigerant expansion chamber in a first direction toward said downstream end plate and then meanders in a second direction opposite that of said first direction toward said second boundary plate, and then returns in said first direction through a refrigerant exit header in hydraulic communication with said low pressure refrigerant outlet.