Abstract: A liquid to refrigerant heat exchanger includes an enclosed coolant volume that is at least partially defined by a plastic housing and by a metal closure plate. The metal closure plate can be part of a brazed assembly containing a continuous refrigerant flow path. The refrigerant flow path is disposed within the coolant volume, where heat can be transferred between the refrigerant within the refrigerant flow path and the liquid within the coolant volume. The plastic housing can at least partially surround the refrigerant flow path to at least partially bound a liquid flow path along a portion of the coolant volume. An inlet diffuser and an outlet diffuser can be mounted to the housing to direct the liquid through the housing. The plastic housing is sealingly joined to the closure plate along an outer periphery of the closure plate.

Abstract: A liquid to refrigerant heat exchanger includes a coolant volume that is at least partially defined by a plastic housing and by a metal closure plate. The plastic housing is sealingly joined to the closure plate along an outer periphery of the closure plate. The metal closure plate can be part of a brazed assembly that defines a continuous refrigerant flow path through the heat exchanger between a refrigerant inlet port and a refrigerant outlet port.

Abstract: A pressure support system for delivering a flow of breathing gas to an airway of a patient includes a base unit structured to generate the flow of breathing gas and including a heating control unit, a conduit coupled to the base unit and structured to carry the flow of breathing gas, a thermistor disposed in the conduit, and first and second resistive wires extending along the conduit from the base unit to the thermistor. The heating control unit is structured to selectively operate in a first mode to heat the conduit using the first and second resistive wires and a second mode to sense a temperature of airflow in the conduit with the thermistor via the first and second resistive wires.

Abstract: A liquid to refrigerant heat exchanger includes a coolant volume that is at least partially defined by a plastic housing and by a metal closure plate. The plastic housing is sealingly joined to the closure plate along an outer periphery of the closure plate. The metal closure plate can be part of a brazed assembly that defines a continuous refrigerant flow path through the heat exchanger between a refrigerant inlet port and a refrigerant outlet port.

Abstract: A liquid to refrigerant heat exchanger includes an enclosed coolant volume that is at least partially defined by a plastic housing and by a metal closure plate. The metal closure plate can be part of a brazed assembly containing a continuous refrigerant flow path. The refrigerant flow path is disposed within the coolant volume, where heat can be transferred between the refrigerant within the refrigerant flow path and the liquid within the coolant volume. The plastic housing can at least partially surround the refrigerant flow path to at least partially bound a liquid flow path along a portion of the coolant volume. An inlet diffuser and an outlet diffuser can be mounted to the housing to direct the liquid through the housing. The plastic housing is sealingly joined to the closure plate along an outer periphery of the closure plate.

Abstract: A pressure support system for delivering a flow of breathing gas to an airway of a patient includes a base unit structured to generate the flow of breathing gas and including a heating control unit, a conduit coupled to the base unit and structured to carry the flow of breathing gas, a thermistor disposed in the conduit, and first and second resistive wires extending along the conduit from the base unit to the thermistor. The heating control unit is structured to selectively operate in a first mode to heat the conduit using the first and second resistive wires and a second mode to sense a temperature of airflow in the conduit with the thermistor via the first and second resistive wires.

Abstract: A pressure support device implements compensation for variations in air density of its operating environment. A pressurized flow of breathable gas is generated for delivery to the airway of a subject. One or more parameters associated with the ambient environment of the pressure support device are determined. These parameters can include one or more of an ambient barometric air pressure, an ambient air temperature, or ambient air humidity. In some embodiments, one or more assumed parameters associated with the ambient environment of the pressure support device are determined based on typical sleeping conditions of the subject. An ambient air density of the ambient environment of the pressure support device is estimated based on one or more of the parameters and/or assumed parameters. A flow rate of the pressurized flow of breathable gas is adjusted based on the estimated ambient air density of the ambient environment of the pressure support device.

Abstract: A device (12) that uses a temperature coefficient pre-calibrated for the device for measuring a flow within the device. The device includes a differential pressure sensor (80) configured to generate a differential pressure signal responsive to a differential pressure within a flow path (16) and a temperature sensor configured to sense a temperature near the differential pressure sensor. A differential amplifier amplifies differential pressure signals from the differential pressure sensor. A processor receives signals from the differential pressure sensor, amplified signals from the differential amplifier, and signals from the temperature sensor. The amplified signals are corrected based upon at least a predetermined temperature coefficient, and the processor calculates a flow rate based on the corrected representation of the differential pressure.

Abstract: A humidifier for use with a pressure support system. The humidifier includes a body having an inlet, a fluid holding chamber, and an outlet. The inlet is positioned upstream and in fluid communication with the fluid holding chamber. The outlet is positioned downstream of and in fluid communication with the fluid holding chamber. A back-flow preventing valve is positioned upstream of the fluid chamber. The back-flow preventing valve is movable between an open position, in which the inlet is unblocked, and a closed position in which the inlet is blocked. In the closed position, the back-flow preventing valve prevents fluid, fluid vapor, or both from entering the pressure support via the inlet to the humidifier.

Abstract: A humidifier for use with a pressure support system. The humidifier includes a body having an inlet, a fluid holding chamber, and an outlet. The inlet is positioned upstream and in fluid communication with the fluid holding chamber. The outlet is positioned downstream of and in fluid communication with the fluid holding chamber. A back-flow preventing valve is positioned upstream of the fluid chamber. The back-flow preventing valve is movable between an open position, in which the inlet is unblocked, and a closed position in which the inlet is blocked. In the closed position, the back-flow preventing valve prevents fluid, fluid vapor, or both from entering the pressure support via the inlet to the humidifier.

Abstract: A pressure support device implements compensation for variations in air density of its operating environment. A pressurized flow of breathable gas is generated for delivery to the airway of a subject. One or more parameters associated with the ambient environment of the pressure support device are determined. These parameters can include one or more of an ambient barometric air pressure, an ambient air temperature, or ambient air humidity. In some embodiments, one or more assumed parameters associated with the ambient environment of the pressure support device are determined based on typical sleeping conditions of the subject. An ambient air density of the ambient environment of the pressure support device is estimated based on one or more of the parameters and/or assumed parameters. A flow rate of the pressurized flow of breathable gas is adjusted based on the estimated ambient air density of the ambient environment of the pressure support device.

Abstract: A method for calibrating a temperature compensation coefficient for a device (12) that utilizes flow. The device includes a flow path (16) and a flow restriction portion (14) in the flow path to create a pressure differential in the flow path. The method includes calculating a temperature compensation coefficient and obtaining a first temperature and a first differential pressure reading at a first time period before flow is generated through the device, and obtaining a second temperature and a second differential pressure reading at a second time period after flow is generated through the device. The method further includes obtaining a compensated differential pressure value based on the temperature compensation coefficient, the measured first temperature, the first differential pressure reading, the measured second temperature, and the second differential pressure reading. The method also includes obtaining the flow within the flow path as a function of the compensated differential pressure value.

Abstract: A device (12) that uses a temperature coefficient pre-calibrated for the device for measuring a flow within the device. The device includes a differential pressure sensor (80) configured to generate a differential pressure signal responsive to a differential pressure within a flow path (16) and a temperature sensor configured to sense a temperature near the differential pressure sensor. A differential amplifier amplifies differential pressure signals from the differential pressure sensor. A processor receives signals from the differential pressure sensor, amplified signals from the differential amplifier, and signals from the temperature sensor. The amplified signals are corrected based upon at least a predetermined temperature coefficient, and the processor calculates a flow rate based on the corrected representation of the differential pressure.

Abstract: The present invention provides a water vaporizer including a first flow path connected to a water inlet, a second flow path for receiving superheated water vapor from the first flow path and being connected to a vapor outlet to exhaust the superheated water vapor, and a third flow path extending between an exhaust inlet and an exhaust outlet and being oriented to transfer heat from an exhaust flow to the superheated water vapor. The water vaporizer can also include a first convoluted fin positioned along the second flow path, and a second convoluted fin positioned along the second flow path adjacent to and separated from the first fin to define a gap extending between the first and second fins along a length of the first fin in a direction substantially parallel to the exhaust flow along the third flow path.