Low-drag, high-efficiency microchannel polymer heat exchangers

A method for operating a polymer heat exchanger with flow passages, comprising:

• directing a liquid through a liquid flow pathway in the polymer heat exchanger, wherein the liquid flow pathway is from a liquid inlet, through internal flow passages in a set of plates, to a liquid outlet, wherein the internal flow passages within the set of plates include arrays of fins of uniform height, which plates are comprised of a polymer and are organized into a stack, wherein the stack has a depth, and wherein consecutive plates in the stack of plates are separated by fins of uniform height to form intervening air passages;
• and
• directing air through an airflow pathway in the polymer heat exchanger, which flows from an airflow inlet, through the intervening air passages between the consecutive plates in the stack of plates, to an airflow outlet;
• wherein the liquid flow pathway is in a direction opposite to a direction of the airflow pathway to provide a counterflow design that optimizes heat transfer between the liquid flow pathway and the airflow pathway;
• and
• wherein each plate in the set of plates includes a plurality of liquid plena positioned in a lateral direction in relation to the liquid flow pathway, wherein the liquid plena in the individual plates form continuous liquid plena in the depth of the stack, wherein the liquid plena are configured to carry liquid from the liquid inlet to the internal flow passages and from the internal flow passages to the liquid outlet in a counterflow design, and wherein the liquid plena extend within and across the air passages to allow airflow around and between the liquid plena.

A heating and/or cooling system for a building, comprising:

• an external heat pump located outside of the building, which uses a low global warming potential (GWP) refrigerant;
• a refrigerant-to-liquid heat exchanger located outside of the building, which exchanges heat between the low GWP refrigerant from the external heat pump and a heat-transfer liquid;
• and
• a polymer heat exchanger located inside the building, which exchanges heat between the heat-transfer liquid from the refrigerant-to-liquid heat exchanger and air, which flows through a heating and/or cooling system in the building;
• wherein the polymer heat exchanger comprises:
• a set of plates comprised of a polymer that includes internal flow passages which are configured to carry a liquid, wherein the internal flow passages within the set of plates include arrays of fins of uniform height;
• wherein the set of plates is organized into a stack, wherein consecutive plates in the stack are separated by fins of uniform height to form intervening air passages, and wherein the stack has a depth;
• wherein the polymer heat exchanger includes a liquid flow pathway from a liquid inlet, through the internal flow passages in the stack of plates, to a liquid outlet;
• wherein the polymer heat exchanger includes an airflow pathway from an airflow inlet, through the intervening air passages between the consecutive plates in the stack of plates, to an airflow outlet;
• wherein the liquid flow pathway flows in a direction opposite to a direction of the airflow pathway to provide a counterflow design that optimizes heat transfer between the liquid flow pathway and the airflow pathway;
• and
• wherein each plate in the set of plates includes a plurality of plena positioned in a lateral direction in relation to the liquid flow pathway, wherein the liquid plena in the individual plates form continuous liquid plena in the depth of the stack, wherein the liquid plena are configured to carry liquid from the liquid inlet to the internal flow passages and from the internal flow passages to the liquid outlet in a counterflow design, and wherein the liquid plena extend within and across the air passages to allow airflow around and between the liquid plena.

A system that provides a heat exchanger, comprising:

• a set of plates that includes internal flow passages, which are configured to carry a liquid, wherein the internal flow passages within the set of plates include arrays of fins of uniform height;
• wherein the set of plates is organized into a stack, wherein consecutive plates in the stack are separated by fins of uniform height to form intervening air passages, and wherein the stack has a depth;
• wherein the heat exchanger includes a liquid flow pathway from a liquid inlet, through the internal flow passages in the stack of plates, to a liquid outlet;
• wherein the heat exchanger includes an airflow pathway from an airflow inlet, through the intervening air passages between the consecutive plates in the stack of plates, to an airflow outlet;
• wherein the liquid flow pathway flows in a direction opposite to a direction of the airflow pathway to provide a counterflow design that optimizes heat transfer between the liquid flow pathway and the airflow pathway;
• and
• wherein each plate in the set of plates includes a plurality of liquid plena positioned in a lateral direction in relation to the liquid flow pathway, wherein the liquid plena in the individual plates form continuous liquid plena in the depth of the stack, wherein the liquid plena are configured to carry liquid from the liquid inlet to the internal flow passages and from the internal flow passages to the liquid outlet in a counterflow design, and wherein the liquid plena extend within and across the air passages to allow airflow around and between the liquid plena.