WO2022184894A1 - Hvac heat recovery system - Google Patents

Hvac heat recovery system Download PDF

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Publication number
WO2022184894A1
WO2022184894A1 PCT/EP2022/055554 EP2022055554W WO2022184894A1 WO 2022184894 A1 WO2022184894 A1 WO 2022184894A1 EP 2022055554 W EP2022055554 W EP 2022055554W WO 2022184894 A1 WO2022184894 A1 WO 2022184894A1
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WO
WIPO (PCT)
Prior art keywords
air
flow
heat exchanger
air heat
cabin
Prior art date
Application number
PCT/EP2022/055554
Other languages
French (fr)
Inventor
Leif Eriksson
Ingemar FORS
Lars Andersson
Jonas NYMAN
Original Assignee
National Electric Vehicle Sweden Ab
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by National Electric Vehicle Sweden Ab filed Critical National Electric Vehicle Sweden Ab
Publication of WO2022184894A1 publication Critical patent/WO2022184894A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60H—ARRANGEMENTS OF HEATING, COOLING, VENTILATING OR OTHER AIR-TREATING DEVICES SPECIALLY ADAPTED FOR PASSENGER OR GOODS SPACES OF VEHICLES
    • B60H1/00—Heating, cooling or ventilating [HVAC] devices
    • B60H1/02—Heating, cooling or ventilating [HVAC] devices the heat being derived from the propulsion plant
    • B60H1/03—Heating, cooling or ventilating [HVAC] devices the heat being derived from the propulsion plant and from a source other than the propulsion plant
    • B60H1/039—Heating, cooling or ventilating [HVAC] devices the heat being derived from the propulsion plant and from a source other than the propulsion plant from air leaving the interior of the vehicle, i.e. heat recovery
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60H—ARRANGEMENTS OF HEATING, COOLING, VENTILATING OR OTHER AIR-TREATING DEVICES SPECIALLY ADAPTED FOR PASSENGER OR GOODS SPACES OF VEHICLES
    • B60H1/00—Heating, cooling or ventilating [HVAC] devices
    • B60H1/00357—Air-conditioning arrangements specially adapted for particular vehicles
    • B60H1/00385—Air-conditioning arrangements specially adapted for particular vehicles for vehicles having an electrical drive, e.g. hybrid or fuel cell
    • B60H1/00392—Air-conditioning arrangements specially adapted for particular vehicles for vehicles having an electrical drive, e.g. hybrid or fuel cell for electric vehicles having only electric drive means
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60H—ARRANGEMENTS OF HEATING, COOLING, VENTILATING OR OTHER AIR-TREATING DEVICES SPECIALLY ADAPTED FOR PASSENGER OR GOODS SPACES OF VEHICLES
    • B60H1/00—Heating, cooling or ventilating [HVAC] devices
    • B60H1/00642—Control systems or circuits; Control members or indication devices for heating, cooling or ventilating devices
    • B60H1/00735—Control systems or circuits characterised by their input, i.e. by the detection, measurement or calculation of particular conditions, e.g. signal treatment, dynamic models
    • B60H1/00785—Control systems or circuits characterised by their input, i.e. by the detection, measurement or calculation of particular conditions, e.g. signal treatment, dynamic models by the detection of humidity or frost
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60H—ARRANGEMENTS OF HEATING, COOLING, VENTILATING OR OTHER AIR-TREATING DEVICES SPECIALLY ADAPTED FOR PASSENGER OR GOODS SPACES OF VEHICLES
    • B60H1/00—Heating, cooling or ventilating [HVAC] devices
    • B60H1/00642—Control systems or circuits; Control members or indication devices for heating, cooling or ventilating devices
    • B60H1/00735—Control systems or circuits characterised by their input, i.e. by the detection, measurement or calculation of particular conditions, e.g. signal treatment, dynamic models
    • B60H1/008—Control systems or circuits characterised by their input, i.e. by the detection, measurement or calculation of particular conditions, e.g. signal treatment, dynamic models the input being air quality
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60H—ARRANGEMENTS OF HEATING, COOLING, VENTILATING OR OTHER AIR-TREATING DEVICES SPECIALLY ADAPTED FOR PASSENGER OR GOODS SPACES OF VEHICLES
    • B60H1/00—Heating, cooling or ventilating [HVAC] devices
    • B60H1/00642—Control systems or circuits; Control members or indication devices for heating, cooling or ventilating devices
    • B60H1/00735—Control systems or circuits characterised by their input, i.e. by the detection, measurement or calculation of particular conditions, e.g. signal treatment, dynamic models
    • B60H1/00807—Control systems or circuits characterised by their input, i.e. by the detection, measurement or calculation of particular conditions, e.g. signal treatment, dynamic models the input being a specific way of measuring or calculating an air or coolant temperature
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60H—ARRANGEMENTS OF HEATING, COOLING, VENTILATING OR OTHER AIR-TREATING DEVICES SPECIALLY ADAPTED FOR PASSENGER OR GOODS SPACES OF VEHICLES
    • B60H1/00—Heating, cooling or ventilating [HVAC] devices
    • B60H1/00642—Control systems or circuits; Control members or indication devices for heating, cooling or ventilating devices
    • B60H1/00814—Control systems or circuits characterised by their output, for controlling particular components of the heating, cooling or ventilating installation
    • B60H1/00821—Control systems or circuits characterised by their output, for controlling particular components of the heating, cooling or ventilating installation the components being ventilating, air admitting or air distributing devices
    • B60H1/00835—Damper doors, e.g. position control

Definitions

  • the present invention relates to an automotive HVAC system adapted to recover heat from the vehicle cabin.
  • the cabin air is evacuated from the vehicle through specific air evacuation valves.
  • the entry of supply air to the cabin is then facilitated by separate supply valves.
  • Dealing with variations in temperature, the air supplied to the cabin has to be heated or cooled in order to comply with passenger comfort. This is a substantial energy investment, especially for electrical vehicles (EVs) since an electrical engine does not produce as much residual heat as a combustion engine.
  • EVs electrical vehicles
  • An object of the present invention is therefore to alleviate at least some of the abovementioned problems with the current state of the art.
  • a cabin air heat recovery system for an electrical vehicle, the system comprising: an air-to-air heat exchanger adapted to transfer heat between a first flow to be supplied to the cabin of the electrical vehicle and a second flow to be exhausted from a cabin of the electrical vehicle; at least one sensor for measuring a first input parameter from the air-to-air heat exchanger or air of the second flow; a recirculation valve for recirculating a volume of air of the second flow to the first flow, wherein the recirculation valve is adapted to recirculate the volume of air of the second flow to the first flow upstream of the air-to-air heat exchanger, or for diverting a volume of air of the first flow to the second flow, wherein the recirculation valve is adapted to divert the volume of air of the first flow to the second flow upstream of the air-to-air heat exchanger; and a control unit configured to control the recirculation valve and thereby the volume of air of the second flow to be
  • a volume of air of the first flow or the second flow could be defined in terms of an absolute volume, or in terms of volume per time unit.
  • a specific amount of volume of a flow may be recirculated/diverted to the other flow.
  • a volume per time unit of a flow may be recirculated/diverted to the other flow
  • a cabin air heat recovery system By providing a cabin air heat recovery system according to the first aspect of the present invention, energy from air that is exhausted from the cabin to the surrounding of the vehicle is recovered by transfer to the air that is to be supplied to the cabin. As such, a more energy efficient system is provided. Furthermore, by recirculating at least part of one of the first or the second flow to the other, multiple parameters of the air-to-air heat exchanger may be controlled. For example, the temperature gradient/s and/or pressure gradient/s and/or flow volume/s over the air-to-air heat exchanger may be controlled. As such, if e.g.
  • the first flow to be supplied to the cabin has a temperature below the freeze point for water at the present conditions
  • warmer air from the second flow may be recirculated into the first flow such that the inlet temperature of the first flow of the air-to-air heat exchanger is raised in order to prevent ice buildup in the air-to-air heat exchanger.
  • the amount of recirculation from one flow to another flow may e.g. be 100%, or 70%, or 50%, or 25%, or 10%.
  • the system further comprises an auxiliary heater and/or a cooler.
  • any flow of air may be further heated or cooled.
  • the first input parameter is a temperature value measured by at least one temperature sensor.
  • the system may sense when the temperature e.g. drops below the freezing point for water at the present conditions.
  • the temperature sensor may e.g. be arranged downstream of the air-to-air heat exchanger in the first flow or downstream of the air-to-air heat exchanger in the second flow. Alternatively, the temperature sensor may be arranged within the air-to-air heat exchanger.
  • the at least one temperature sensor is arranged in the second flow downstream the air-to-air heat exchanger.
  • the air of the first flow will in general have a lower temperature than the air of the second flow.
  • the second flow downstream of the air-to-air heat exchanger will be colder than upstream of the air-to-air heat exchanger.
  • the first input parameter is a humidity level of the second flow measured by a humidity sensor.
  • the system may sense that the humidity of the cabin air is too high, i.e. that the humidity surpasses a preferred threshold value. As such, less air of the second flow may be recirculated to the first flow, i.e. less of the air with a high humidity may be recirculated back into the cabin.
  • the first input parameter is a CO 2 level of the second flow measured by a CO 2 sensor.
  • the CO 2 level in the vehicle cabin is monitored.
  • the volume of air of the second flow to be recirculated in the first flow may be limited if the CO 2 level is at a certain threshold, or exceeding a certain threshold, or is close to a certain threshold.
  • the system comprising a first sensor for measuring a first input parameter and a second sensor for measuring a second input parameter.
  • the first input parameter is a temperature value measured by at least one temperature sensor and wherein the second input parameter is a humidity of the second flow measured by a humidity sensor.
  • the air-to-air heat exchanger comprises a plurality of channels and wherein the recirculation valve is adapted to control the flow of the first volume of the second flow to at least one of said plurality of channels based on the first and/or second input parameter.
  • the system further comprises a dry mode valve adapted to recirculate at least a part of the first flow downstream of the air-to-air heat exchanger via the auxiliary heater and to the first flow upstream of the air-to-air heat exchanger.
  • incoming supply air drawn into the system may be further preconditioned before entering the air-to-air heat exchanger.
  • a method for operating an air-to-air heat exchanger in a cabin air energy reuse system may comprise preventing ice buildup.
  • the method comprises the steps: measuring a temperature T1 of the air-to-air heat exchanger with at least one temperature sensor; and if T1 is equal to or below a predetermined temperature threshold value, opening the recirculation valve such that at least a part of the second flow is recirculated to the first flow.
  • the temperature in the air-to-air heat exchanger may be raised such that buildup of ice is prevented.
  • the inlet temperature of the first flow of the air-to-air heat exchanger is raised in order to prevent ice buildup in the air-to-air heat exchanger.
  • the predetermined threshold may e.g. be the freezing point for water under present conditions.
  • the method further comprises: measuring a temperature T2 of at least one of a plurality of channels of the air-to-air heat exchanger, and directing the at least part of the second flow to said at least one of a plurality of channels if the temperature T2 is below said predetermined value.
  • the method further comprises: measuring a first humidity level of the second flow with a humidity sensor, and wherein the amount of the second flow to be recirculated to the first flow by the recirculation valve is determined by the first humidity level.
  • the system may increase or decrease the amount of the second flow to be recirculated to the first flow such that a preferred level of humidity in the cabin is maintained.
  • the method further comprises: measuring a CO2 level of the second flow with a CO2 sensor, and wherein the amount of the second flow to be recirculated to the first flow by the recirculation valve is determined by the CO2 level.
  • the method further comprises evacuating condensate by: after performing the steps in any preceding exemplary embodiment of the second aspect, closing the recirculation valve; opening a dry mode valve such that at least a part of said first flow downstream of the air-to-air heat exchanger is recirculated to said first flow upstream of the air-to-air heat exchanger; and opening the recirculation valve such that part of the first flow is diverted to the second flow.
  • Evacuating condensate is thus performed after the step of opening the recirculation valve such that at least a part of the second flow is recirculated to the first flow, or after the step of directing the at least part of the second flow to said at least one of a plurality of channels if the temperature T2 is below said predetermined value.
  • Evacuating condensate is moreover normally performed when the vehicle is standing still, such as when the vehicle is parked and non-operating after having been operated.
  • condensate may be accumulated in the air-to-air heat exchanger.
  • the step of evacuating condensate aims at solving the problem of accumulated condensate in a heat recovery system according to the present invention.
  • Evacuating condensate may alternatively be performed independent of previous steps of the second aspect of the present invention, i.e. evacuating condensate may be performed independent of whether the heat recovery system has been operated according to previous steps.
  • the method further comprises: heating the first flow with an auxiliary heater.
  • the air-to-air heat exchanger By heating the air of the first flow, when the air is recirculated and passed through the air-to-air heat exchanger, the air-to-air heat exchanger is heated up. As such, the transfer of condensate is further facilitated by evaporation due to the increased temperature of the air-to-air heat exchanger.
  • Fig. 1 is a schematic drawing of a cabin air reuse system according to the first aspect of the present invention.
  • Fig. 2 is a schematic drawing of the cabin air reuse system in Fig. 1 , wherein the system is adapted to perform the method according to the third aspect of the present invention.
  • Fig. 3 is a diagram of the second aspect of the present invention.
  • Fig. 4 is a diagram of the method of evacuating condensate according to the second aspect of the present invention.
  • a cabin air reuse system 1 for a vehicle comprising an air-to-air heat exchanger 2 is provided.
  • Supply air is drawn into the system 1 by a supply fan 3, and enters through a first valve 5.
  • the supply air is subsequently passed through the air-to-air heat exchanger 2 such that the supply air constitutes a first flow F1 through the system 1 and the air-to-air heat exchanger 2, where it is adapted to exchange heat with a second flow F2 to be exhausted from the vehicle.
  • the air-to-air heat exchanger 2 may be any type of air-to-air heat exchanger.
  • the air-to-air heat exchanger 2 may be a plate heat exchanger.
  • the first flow F1 and the second flow F2 is in Fig. 1 shown in a cross-flow arrangement.
  • the first flow F1 and the second flow F2 may be arranged in a counter cross-flow arrangement or a parallel flow arrangement.
  • the supply air of the first flow F1 is then passed into an air conditioning unit 7.
  • the air conditioning unit 7 may e.g. be a standard air conditioning unit used in vehicles.
  • the air conditioning unit 7 may further comprise a heater 8 and/or a cooler (not shown) for further condition the first flow F1 of air to be supplied to the cabin (not shown) of the vehicle.
  • a second flow F2 of cabin air that is to be exhausted from the vehicle is brought into the system by an exhaust fan 9.
  • the cabin air is brought through a recirculation valve 11.
  • the recirculation valve 11 is a three-way valve such that at least part of the cabin air of the second flow F2 may be recirculated to the first flow F1.
  • the recirculation valve 11 may permit at least part of the first flow F1 to be diverted to the second flow F2. Whether the first flow F1 is diverted to the second flow F2 or the second flow F2 is recirculated to the first flow F1 may e.g. be determined by the relative pressures of the first flow F1 and the second flow F2. For example, by operating the supply fan 3 at a higher pressure than the exhaust fan 9, the first S F1 flow may be diverted to the second flow F2. Correspondingly, if the exhaust fan 9 is operated at a higher pressure than the supply fan 3, the second flow F2 may be recirculated to the first flow F1.
  • the point P1 at which the second flow F2 is recirculated to the first flow F1 is here shown as being arranged upstream of the air-to-air heat exchanger 2.
  • the point P1 may alternatively be arranged directly in the air-to-air heat exchanger 2.
  • the cabin air of the second flow F2 is further passed into the air air- to-air heat exchanger 2 in which it exchanges heat with the first flow F 1 , after which it is exhausted from the system 1.
  • the system 1 further comprises a control unit 14 electrically and/or electronically connected to the supply fan 3 and the exhaust fan 9. As such, the control unit 14 is arranged to coordinate the operation of the respective fans 3, 9 such that the desired flow rates throughout the system as well as the desired pressure of the cabin may be achieved.
  • the control unit 14 is further electrically and/or electronically connected to a temperature sensor 15 arranged to measure a temperature of the air-to-air heat exchanger 2.
  • the temperature sensor 15 may e.g. be arranged downstream of the air-to-air heat exchanger 2 in the first flow F1 or downstream of the air-to-air heat exchanger 2 in the second flow F2. Alternatively, the temperature sensor 15 may be arranged within the air-to-air heat exchanger 2.
  • the system may sense when the temperature e.g. drops below the freezing point for water at the present conditions.
  • the control unit 14 may e.g. increase the pressure in the second flow F2 such that more air from the second flow F2 is recirculated to the first flow F 1 , provided that the temperature of the second flow F2 is higher than the temperature of the first flow F1.
  • the control unit 14 is further electrically and/or electronically connected to a humidity sensor 19 arranged to measure a humidity level of the second flow F2.
  • the control unit 14 is furthermore electrically and/or electronically connected to the recirculation valve 11 such that the control unit 14 is arranged to operate the recirculation valve 11.
  • the system 1 may sense that the humidity of the cabin air is too high, i.e. that the humidity surpasses a preferred threshold value.
  • the control unit 14 may modulate the recirculation valve 11 such that less air of the second flow F2 is recirculated to the first flow F 1 , i.e. less of the air with a high humidity may be recirculated back into the cabin of the vehicle.
  • the system 1 may further comprise a CO2 sensor (not shown) for measuring a CO2 level of the second flow F2, which measure may be used as input for controlling the volume of the second flow F2 that is recirculated to the first flow F1.
  • a CO2 sensor (not shown) for measuring a CO2 level of the second flow F2, which measure may be used as input for controlling the volume of the second flow F2 that is recirculated to the first flow F1.
  • the first valve 5 is further arranged such that it may permit recirculation of the first flow F1 downstream of the air-to-air heat exchanger 2 back to itself at a point upstream of the air-to-air heat exchanger 2.
  • the first valve 5 may permit recirculation of at least a part of the air of the first flow F1 exiting the air conditioning unit 7.
  • conditioned air e.g. heated air
  • the point from which the air of the first flow F1 is to be recirculated upstream of the air-to-air heat exchanger 2 may be arranged upstream of the air conditioning unit 7.
  • Fig. 2 the system 1 is shown during dry mode operation.
  • dry mode condensate accumulated in the air-to-air heat exchanger 2 during normal operation, i.e. under normal operation of the vehicle during which supply air mixed with cabin is passed through the air-to-air heat exchanger 2, is to be evacuated from the system 1.
  • the exhaust fan 9 is not operating so that there is no air from the cabin of the vehicle in the second flow F2, and the recirculation valve 11 is closed against the exhaust fan 9.
  • the recirculation valve 11 is closed such that no amount of air of the first flow F1 is diverted to the second flow F2.
  • the first valve 5 (may also be referred to as a “dry mode valve”) is open so as to permit recirculation of at least a part of the air of the first flow F1 exiting the air conditioning unit 7.
  • the air of the first flow F1 pass the air-to-air heat exchanger 2 multiple times, condensate in the air-to-air heat exchanger 2 is transferred to the first flow F1.
  • the air may e.g. be recirculated to the degree such that it is saturated with humidity.
  • the recirculation valve 11 is open such that at least a part of the first flow F1 is diverted to the second flow F2. As such, the air of the first flow F1 is exhausted from the system 1.
  • the air of the first flow F1 is heated by the heater 8 of the air conditioning unit 7.
  • the air-to-air heat exchanger 2 is heated up.
  • the transfer of condensate is further facilitated by evaporation due to the increased temperature of the air-to-air heat exchanger 3.
  • Fig. 3 shows a diagram of the second aspect of the present invention relating to a method for e.g. preventing ice buildup in the air-to-air heat exchanger 2 of the system 1.
  • Measuring S1 a temperature T1 of second flow is performed during a first step. If the temperature T 1 of the second flow is below or equal to a predetermined temperature threshold value Th, opening S4 the recirculation valve 11 is performed.
  • the predetermined temperature threshold value Th may e.g. be the freezing point of water under present conditions. Th may thus e.g. be 0°C.
  • Th may alternatively be a value above the freezing point of water at atmospheric pressure, such as 1 °C, 2°C or 5°C.
  • Th may alternatively be a value below the freezing point of water at atmospheric pressure, such as -1°C, -2°C or -5°C.
  • the method may further comprise measuring S2 a humidity value H1 of the second flow F2. Subsequent to measuring S3 a humidity value H 1 of the second flow F2, the step of opening S4 the recirculation valve 11 is performed. As such, the amount of the second flow F2 that is recirculated to the first flow F1 through the recirculation valve 11 may be determined by the humidity value H 1. Thus, the humidity value H 1 may be compared to a humidity threshold value. As such, the recirculation valve 11 may be partially closed, or fully closed, if the humidity value H 1 exceeds a humidity threshold value.
  • a humidity threshold value may e.g.
  • a humidity threshold value may be dynamically set due to requirements imposed by passengers, or by changes in the humidity of the air ambient to the vehicle.
  • a CO2 level of the second flow F2 may be measured and used as input for controlling the volume of the second flow F2 that is recirculated to the first flow F1.
  • measuring S4 a temperature T2 of the air-to- air heat exchanger 2 is performed. The temperature T2 air-to-air heat exchanger 2 may be compared to the predetermined temperature threshold value Th.
  • the method may further comprise directing S5 the air of the second flow F2 that is recirculated to the first flow F1 to a specific channel of a plurality of channels of the air-to-air heat exchanger 2, or to some of the plurality of channels of the air-to-air heat exchanger 2.
  • directing S5 the air of the second flow F2 that is recirculated to the first flow F1 to a specific channel of a plurality of channels of the air-to-air heat exchanger 2, or to some of the plurality of channels of the air-to-air heat exchanger 2.
  • measuring S4 T2 may be performed at the same time as measuring S1 T1.
  • measuring S1 the temperature of the second flow T1 may be the same step as measuring S4 the temperature of the air-to-air heat exchanger 2, i.e. there is only one temperature sensor in the system 1.
  • Fig. 4 shows a diagram of the third aspect of the present invention relating to a method for evacuating condensate in an air-to-air heat exchanger 2 in a cabin air energy reuse system according to the first aspect of the present invention.
  • Closing S10 the recirculation valve 11 prevents any air from the second flow F2 to be recirculated to the first flow F1.
  • the second flow F2 is closed towards the cabin of the vehicle such that there is no air in the second flow 2.
  • Opening S11 a dry mode valve 5 permits recirculation of at least a part of the air of the first flow F1 downstream of the air-to-air heat exchanger 2 back to the first flow F1 upstream of air-to-air heat exchanger 2.
  • the step of opening S11 the dry mode valve 5 may have a variable duration. For example, the duration may be 1 minute, or 2 minutes, or 5 minutes, or 10 minutes.
  • Opening S13 the recirculation valve 11 permits the air of the first flow F1 to be diverted to the second flow F2.
  • the air of the first flow F1 is exhausted from the system 1.
  • Condensate in the air-to-air heat exchanger 2 on the side of the first flow F1 will then be evacuated due to the flow and pressure of the air from the first flow F1 that is diverted to the second flow F2.
  • heating S12 is performed.
  • the air of the first flow F1 is heated by a heater 8.
  • the heater 8 may e.g. be arranged in a air conditioning unit 7.
  • the air-to-air heat exchanger 2 is heated up.
  • the transfer of condensate is further facilitated by evaporation due to the increased temperature of the air-to-air heat exchanger 2.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Air-Conditioning For Vehicles (AREA)

Abstract

The present invention relates to a cabin air energy reuse system for an electrical vehicle comprising: an air-to-air heat exchanger adapted to transfer heat between a first flow to be supplied to the cabin of the electrical vehicle and a second flow to be exhausted from a cabin of the electrical vehicle; and a recirculation valve for recirculating at least a part of the second flow to the first flow, wherein said recirculation valve is adapted to recirculate said at least a part of the second flow to the first flow upstream of said air-to-air heat exchanger, or for recirculating at least a part of the first flow to the second flow, wherein said recirculation valve is adapted to recirculate said at least a part of the first flow to the second flow upstream of said air-to-air heat exchanger.

Description

HVAC heat recovery system
Technical field
The present invention relates to an automotive HVAC system adapted to recover heat from the vehicle cabin.
Background of the invention
In a traditional automotive HVAC system, the cabin air is evacuated from the vehicle through specific air evacuation valves. The entry of supply air to the cabin is then facilitated by separate supply valves. Dealing with variations in temperature, the air supplied to the cabin has to be heated or cooled in order to comply with passenger comfort. This is a substantial energy investment, especially for electrical vehicles (EVs) since an electrical engine does not produce as much residual heat as a combustion engine.
In both warm and cold climates, the air of the cabin may thus be recirculated in order to conserve energy. However, there are substantial drawbacks with recirculation of air. First and foremost, this increases the risk of condensation on screens due to high humidity of the air. Air recirculation is further limited by the reduced quality of the air from the perspective of the passengers, such as unpleasant odors or high concentrations of C02.
Summary of the invention
An object of the present invention is therefore to alleviate at least some of the abovementioned problems with the current state of the art.
According to a first aspect of the present invention, a cabin air heat recovery system for an electrical vehicle is provided, the system comprising: an air-to-air heat exchanger adapted to transfer heat between a first flow to be supplied to the cabin of the electrical vehicle and a second flow to be exhausted from a cabin of the electrical vehicle; at least one sensor for measuring a first input parameter from the air-to-air heat exchanger or air of the second flow; a recirculation valve for recirculating a volume of air of the second flow to the first flow, wherein the recirculation valve is adapted to recirculate the volume of air of the second flow to the first flow upstream of the air-to-air heat exchanger, or for diverting a volume of air of the first flow to the second flow, wherein the recirculation valve is adapted to divert the volume of air of the first flow to the second flow upstream of the air-to-air heat exchanger; and a control unit configured to control the recirculation valve and thereby the volume of air of the second flow to be recirculated to the first flow based on the first input parameter or the volume of air of the first flow to be diverted to the second flow based on the first input parameter.
A volume of air of the first flow or the second flow could be defined in terms of an absolute volume, or in terms of volume per time unit. Thus, a specific amount of volume of a flow may be recirculated/diverted to the other flow. Alternatively, a volume per time unit of a flow may be recirculated/diverted to the other flow
By providing a cabin air heat recovery system according to the first aspect of the present invention, energy from air that is exhausted from the cabin to the surrounding of the vehicle is recovered by transfer to the air that is to be supplied to the cabin. As such, a more energy efficient system is provided. Furthermore, by recirculating at least part of one of the first or the second flow to the other, multiple parameters of the air-to-air heat exchanger may be controlled. For example, the temperature gradient/s and/or pressure gradient/s and/or flow volume/s over the air-to-air heat exchanger may be controlled. As such, if e.g. the first flow to be supplied to the cabin has a temperature below the freeze point for water at the present conditions, warmer air from the second flow may be recirculated into the first flow such that the inlet temperature of the first flow of the air-to-air heat exchanger is raised in order to prevent ice buildup in the air-to-air heat exchanger.
The amount of recirculation from one flow to another flow may e.g. be 100%, or 70%, or 50%, or 25%, or 10%.
According to an exemplary embodiment, the system further comprises an auxiliary heater and/or a cooler.
By providing the system with a heater and/or a cooler, any flow of air may be further heated or cooled.
According to an exemplary embodiment, the first input parameter is a temperature value measured by at least one temperature sensor.
By measuring a temperature of the air-to-air heat exchanger, the system may sense when the temperature e.g. drops below the freezing point for water at the present conditions. The temperature sensor may e.g. be arranged downstream of the air-to-air heat exchanger in the first flow or downstream of the air-to-air heat exchanger in the second flow. Alternatively, the temperature sensor may be arranged within the air-to-air heat exchanger.
According to an exemplary embodiment, the at least one temperature sensor is arranged in the second flow downstream the air-to-air heat exchanger.
During conditions where there is a risk of freezing in the air-to-air heat exchanger, the air of the first flow will in general have a lower temperature than the air of the second flow. As such, the second flow downstream of the air-to-air heat exchanger will be colder than upstream of the air-to-air heat exchanger. Thus, measuring the temperature downstream of the air-to-air heat exchanger is more efficient when predicting freezing of the air-to-air heat exchanger.
According to an exemplary embodiment, the first input parameter is a humidity level of the second flow measured by a humidity sensor.
By measuring the humidity of the second flow, the system may sense that the humidity of the cabin air is too high, i.e. that the humidity surpasses a preferred threshold value. As such, less air of the second flow may be recirculated to the first flow, i.e. less of the air with a high humidity may be recirculated back into the cabin.
According to an exemplary embodiment, the first input parameter is a CO2 level of the second flow measured by a CO2 sensor.
By monitoring the CO2 level of the second flow, the CO2 level in the vehicle cabin is monitored. Thus, the volume of air of the second flow to be recirculated in the first flow may be limited if the CO2 level is at a certain threshold, or exceeding a certain threshold, or is close to a certain threshold.
According to an exemplary embodiment, the system comprising a first sensor for measuring a first input parameter and a second sensor for measuring a second input parameter.
According to an exemplary embodiment, the first input parameter is a temperature value measured by at least one temperature sensor and wherein the second input parameter is a humidity of the second flow measured by a humidity sensor.
According to an exemplary embodiment, the air-to-air heat exchanger comprises a plurality of channels and wherein the recirculation valve is adapted to control the flow of the first volume of the second flow to at least one of said plurality of channels based on the first and/or second input parameter.
By selectively directing a volume of air from the second flow to a subset of the channels of the air-to-air heat exchanger, when recirculating the second flow to the first flow, only the parts of the air-to-air heat exchanger where the temperature is equal to or below the predetermined threshold may be heated. Thus, a smaller amount of air from the second flow needs to be recirculated. Thus, the temperature gradient over the air-to-air heat exchanger is less affected, and freezing is prevented while high heat transfer efficiency is maintained.
According to an exemplary embodiment, the system further comprises a dry mode valve adapted to recirculate at least a part of the first flow downstream of the air-to-air heat exchanger via the auxiliary heater and to the first flow upstream of the air-to-air heat exchanger.
By recirculating at least a part of the first flow downstream of the air-to- air heat exchanger back to first flow at a point upstream of the air-to-air heat exchanger, incoming supply air drawn into the system may be further preconditioned before entering the air-to-air heat exchanger.
According to a second aspect of the present invention, a method for operating an air-to-air heat exchanger in a cabin air energy reuse system according to the first aspect of the present invention is provided. The method may comprise preventing ice buildup. The method comprises the steps: measuring a temperature T1 of the air-to-air heat exchanger with at least one temperature sensor; and if T1 is equal to or below a predetermined temperature threshold value, opening the recirculation valve such that at least a part of the second flow is recirculated to the first flow.
By recirculating cabin air that is warmer than the incoming supply air to the supply air, the temperature in the air-to-air heat exchanger may be raised such that buildup of ice is prevented. By recirculating the warmer second flow to the first flow, the inlet temperature of the first flow of the air-to-air heat exchanger is raised in order to prevent ice buildup in the air-to-air heat exchanger. The predetermined threshold may e.g. be the freezing point for water under present conditions.
According to an exemplary embodiment, the method further comprises: measuring a temperature T2 of at least one of a plurality of channels of the air-to-air heat exchanger, and directing the at least part of the second flow to said at least one of a plurality of channels if the temperature T2 is below said predetermined value.
By selectively directing air from the second flow to a subset of the channels of the air-to-air heat exchanger, when recirculating the second flow to the first flow, only the parts of the air-to-air heat exchanger where the temperature is equal to or below the predetermined threshold may be heated. Thus, a smaller amount of air from the second flow needs to be recirculated. Thus, the temperature gradient over the air-to-air heat exchanger is less affected, and freezing is prevented while high heat transfer efficiency is maintained.
According to an exemplary embodiment, the method further comprises: measuring a first humidity level of the second flow with a humidity sensor, and wherein the amount of the second flow to be recirculated to the first flow by the recirculation valve is determined by the first humidity level.
By monitoring the humidity level of the second flow, the system may increase or decrease the amount of the second flow to be recirculated to the first flow such that a preferred level of humidity in the cabin is maintained.
According to an exemplary embodiment, the method further comprises: measuring a CO2 level of the second flow with a CO2 sensor, and wherein the amount of the second flow to be recirculated to the first flow by the recirculation valve is determined by the CO2 level.
According to an exemplary embodiment, the method further comprises evacuating condensate by: after performing the steps in any preceding exemplary embodiment of the second aspect, closing the recirculation valve; opening a dry mode valve such that at least a part of said first flow downstream of the air-to-air heat exchanger is recirculated to said first flow upstream of the air-to-air heat exchanger; and opening the recirculation valve such that part of the first flow is diverted to the second flow.
Evacuating condensate is thus performed after the step of opening the recirculation valve such that at least a part of the second flow is recirculated to the first flow, or after the step of directing the at least part of the second flow to said at least one of a plurality of channels if the temperature T2 is below said predetermined value. Evacuating condensate is moreover normally performed when the vehicle is standing still, such as when the vehicle is parked and non-operating after having been operated. During normal operation of the vehicle, during which the heat recovery system is operated such that heat is recovered from the second flow to the first flow, condensate may be accumulated in the air-to-air heat exchanger. As such, the step of evacuating condensate aims at solving the problem of accumulated condensate in a heat recovery system according to the present invention. Evacuating condensate may alternatively be performed independent of previous steps of the second aspect of the present invention, i.e. evacuating condensate may be performed independent of whether the heat recovery system has been operated according to previous steps.
By letting the air of the first flow pass the air-to-air heat exchanger, condensate in the air-to-air heat exchanger is transferred to the first flow. As such, when the first is diverted to the second flow, the condensate is evacuated from the system. Furthermore, condensate that is accumulated in the air-to-air heat exchanger on the side of the second flow F2, will by pressure exerted by the air of the first flow F1 when diverted to the second flow F2 be evacuated from the system.
According to an exemplary embodiment, the method further comprises: heating the first flow with an auxiliary heater.
By heating the air of the first flow, when the air is recirculated and passed through the air-to-air heat exchanger, the air-to-air heat exchanger is heated up. As such, the transfer of condensate is further facilitated by evaporation due to the increased temperature of the air-to-air heat exchanger.
Brief description of the drawings
The invention, some non-limiting embodiments, and further advantages of the invention will now be described with references to the drawings, in which:
Fig. 1 is a schematic drawing of a cabin air reuse system according to the first aspect of the present invention.
Fig. 2 is a schematic drawing of the cabin air reuse system in Fig. 1 , wherein the system is adapted to perform the method according to the third aspect of the present invention.
Fig. 3 is a diagram of the second aspect of the present invention.
Fig. 4 is a diagram of the method of evacuating condensate according to the second aspect of the present invention.
Detailed description
In the following detailed description, some embodiments of the present invention will be described. Flowever, it is to be understood that features of the different embodiments are exchangeable between the embodiments and may be combined in different ways, unless anything is specifically indicated. Even though in the following description, numerous details are set forth to provide a more thorough understanding of the present invention, it will be apparent to one skilled in the art that the present invention may be practiced without these details. In other instances, well known constructions or functions are not described in detail, so as not to obscure the present invention. In Fig. 1 a cabin air reuse system 1 for a vehicle (not shown) comprising an air-to-air heat exchanger 2 is provided. Supply air is drawn into the system 1 by a supply fan 3, and enters through a first valve 5. The supply air is subsequently passed through the air-to-air heat exchanger 2 such that the supply air constitutes a first flow F1 through the system 1 and the air-to-air heat exchanger 2, where it is adapted to exchange heat with a second flow F2 to be exhausted from the vehicle. The air-to-air heat exchanger 2 may be any type of air-to-air heat exchanger. For example, the air-to-air heat exchanger 2 may be a plate heat exchanger. Furthermore, the first flow F1 and the second flow F2 is in Fig. 1 shown in a cross-flow arrangement. Alternatively, the first flow F1 and the second flow F2 may be arranged in a counter cross-flow arrangement or a parallel flow arrangement.
The supply air of the first flow F1 is then passed into an air conditioning unit 7. The air conditioning unit 7 may e.g. be a standard air conditioning unit used in vehicles. The air conditioning unit 7 may further comprise a heater 8 and/or a cooler (not shown) for further condition the first flow F1 of air to be supplied to the cabin (not shown) of the vehicle. A second flow F2 of cabin air that is to be exhausted from the vehicle is brought into the system by an exhaust fan 9. The cabin air is brought through a recirculation valve 11. Flere, the recirculation valve 11 is a three-way valve such that at least part of the cabin air of the second flow F2 may be recirculated to the first flow F1. Additionally or alternatively, the recirculation valve 11 may permit at least part of the first flow F1 to be diverted to the second flow F2. Whether the first flow F1 is diverted to the second flow F2 or the second flow F2 is recirculated to the first flow F1 may e.g. be determined by the relative pressures of the first flow F1 and the second flow F2. For example, by operating the supply fan 3 at a higher pressure than the exhaust fan 9, the first S F1 flow may be diverted to the second flow F2. Correspondingly, if the exhaust fan 9 is operated at a higher pressure than the supply fan 3, the second flow F2 may be recirculated to the first flow F1. The point P1 at which the second flow F2 is recirculated to the first flow F1 is here shown as being arranged upstream of the air-to-air heat exchanger 2. The point P1 may alternatively be arranged directly in the air-to-air heat exchanger 2.
The cabin air of the second flow F2 is further passed into the air air- to-air heat exchanger 2 in which it exchanges heat with the first flow F 1 , after which it is exhausted from the system 1.
The system 1 further comprises a control unit 14 electrically and/or electronically connected to the supply fan 3 and the exhaust fan 9. As such, the control unit 14 is arranged to coordinate the operation of the respective fans 3, 9 such that the desired flow rates throughout the system as well as the desired pressure of the cabin may be achieved. The control unit 14 is further electrically and/or electronically connected to a temperature sensor 15 arranged to measure a temperature of the air-to-air heat exchanger 2. The temperature sensor 15 may e.g. be arranged downstream of the air-to-air heat exchanger 2 in the first flow F1 or downstream of the air-to-air heat exchanger 2 in the second flow F2. Alternatively, the temperature sensor 15 may be arranged within the air-to-air heat exchanger 2. By measuring a temperature of the air-to-air heat exchanger 2, the system may sense when the temperature e.g. drops below the freezing point for water at the present conditions. As such, the control unit 14 may e.g. increase the pressure in the second flow F2 such that more air from the second flow F2 is recirculated to the first flow F 1 , provided that the temperature of the second flow F2 is higher than the temperature of the first flow F1.
The control unit 14 is further electrically and/or electronically connected to a humidity sensor 19 arranged to measure a humidity level of the second flow F2. The control unit 14 is furthermore electrically and/or electronically connected to the recirculation valve 11 such that the control unit 14 is arranged to operate the recirculation valve 11. By measuring the humidity of the second flow F2, the system 1 may sense that the humidity of the cabin air is too high, i.e. that the humidity surpasses a preferred threshold value. As such, the control unit 14 may modulate the recirculation valve 11 such that less air of the second flow F2 is recirculated to the first flow F 1 , i.e. less of the air with a high humidity may be recirculated back into the cabin of the vehicle.
The system 1 may further comprise a CO2 sensor (not shown) for measuring a CO2 level of the second flow F2, which measure may be used as input for controlling the volume of the second flow F2 that is recirculated to the first flow F1.
The first valve 5 is further arranged such that it may permit recirculation of the first flow F1 downstream of the air-to-air heat exchanger 2 back to itself at a point upstream of the air-to-air heat exchanger 2. Specifically, the first valve 5 may permit recirculation of at least a part of the air of the first flow F1 exiting the air conditioning unit 7. As such, conditioned air, e.g. heated air, may be recirculated in order to increase the inlet temperature of the first flow F1 to the air-to-air heat exchanger 2. Alternatively, the point from which the air of the first flow F1 is to be recirculated upstream of the air-to-air heat exchanger 2 may be arranged upstream of the air conditioning unit 7.
In Fig. 2, the system 1 is shown during dry mode operation. During dry mode, condensate accumulated in the air-to-air heat exchanger 2 during normal operation, i.e. under normal operation of the vehicle during which supply air mixed with cabin is passed through the air-to-air heat exchanger 2, is to be evacuated from the system 1. During dry mode, the exhaust fan 9 is not operating so that there is no air from the cabin of the vehicle in the second flow F2, and the recirculation valve 11 is closed against the exhaust fan 9. During a first operating state of the dry mode, the recirculation valve 11 is closed such that no amount of air of the first flow F1 is diverted to the second flow F2. During the first operating state of the dry mode, the first valve 5 (may also be referred to as a “dry mode valve”) is open so as to permit recirculation of at least a part of the air of the first flow F1 exiting the air conditioning unit 7. By letting the air of the first flow F1 pass the air-to-air heat exchanger 2 multiple times, condensate in the air-to-air heat exchanger 2 is transferred to the first flow F1. The air may e.g. be recirculated to the degree such that it is saturated with humidity. During a second operating state of the dry mode, the recirculation valve 11 is open such that at least a part of the first flow F1 is diverted to the second flow F2. As such, the air of the first flow F1 is exhausted from the system 1.
In some embodiments, the air of the first flow F1 is heated by the heater 8 of the air conditioning unit 7. Thus, when the air is recirculated and passed through the air-to-air heat exchanger 2, the air-to-air heat exchanger 2 is heated up. As such, the transfer of condensate is further facilitated by evaporation due to the increased temperature of the air-to-air heat exchanger 3.
Fig. 3 shows a diagram of the second aspect of the present invention relating to a method for e.g. preventing ice buildup in the air-to-air heat exchanger 2 of the system 1. Measuring S1 a temperature T1 of second flow is performed during a first step. If the temperature T 1 of the second flow is below or equal to a predetermined temperature threshold value Th, opening S4 the recirculation valve 11 is performed. The predetermined temperature threshold value Th may e.g. be the freezing point of water under present conditions. Th may thus e.g. be 0°C. Th may alternatively be a value above the freezing point of water at atmospheric pressure, such as 1 °C, 2°C or 5°C. Th may alternatively be a value below the freezing point of water at atmospheric pressure, such as -1°C, -2°C or -5°C.
Additionally or alternatively, before performing the step of opening S3 the recirculation valve 11 , the method may further comprise measuring S2 a humidity value H1 of the second flow F2. Subsequent to measuring S3 a humidity value H 1 of the second flow F2, the step of opening S4 the recirculation valve 11 is performed. As such, the amount of the second flow F2 that is recirculated to the first flow F1 through the recirculation valve 11 may be determined by the humidity value H 1. Thus, the humidity value H 1 may be compared to a humidity threshold value. As such, the recirculation valve 11 may be partially closed, or fully closed, if the humidity value H 1 exceeds a humidity threshold value. A humidity threshold value may e.g. be a value at which passengers of the vehicle are uncomfortable. A humidity threshold value may be dynamically set due to requirements imposed by passengers, or by changes in the humidity of the air ambient to the vehicle. Alternatively or additionally, a CO2 level of the second flow F2 may be measured and used as input for controlling the volume of the second flow F2 that is recirculated to the first flow F1. In some embodiments, measuring S4 a temperature T2 of the air-to- air heat exchanger 2 is performed. The temperature T2 air-to-air heat exchanger 2 may be compared to the predetermined temperature threshold value Th. The method may further comprise directing S5 the air of the second flow F2 that is recirculated to the first flow F1 to a specific channel of a plurality of channels of the air-to-air heat exchanger 2, or to some of the plurality of channels of the air-to-air heat exchanger 2. As such, only a channel or channels where the temperature T1 is equal to or below the threshold temperature value Th is heated up by the warmer air from the second flow S2. As such, the overall temperature efficiency of the air-to-air heat exchanger 2 is less influenced.
Alternatively, measuring S4 T2 may be performed at the same time as measuring S1 T1. Alternatively, measuring S1 the temperature of the second flow T1 may be the same step as measuring S4 the temperature of the air-to-air heat exchanger 2, i.e. there is only one temperature sensor in the system 1.
Fig. 4 shows a diagram of the third aspect of the present invention relating to a method for evacuating condensate in an air-to-air heat exchanger 2 in a cabin air energy reuse system according to the first aspect of the present invention.
Closing S10 the recirculation valve 11 prevents any air from the second flow F2 to be recirculated to the first flow F1. Preferably, the second flow F2 is closed towards the cabin of the vehicle such that there is no air in the second flow 2.
Opening S11 a dry mode valve 5 permits recirculation of at least a part of the air of the first flow F1 downstream of the air-to-air heat exchanger 2 back to the first flow F1 upstream of air-to-air heat exchanger 2. By letting the air of the first flow F1 pass the air-to-air heat exchanger 2 multiple times, condensate in the air-to-air heat exchanger 2 is transferred to the first flow F1. The step of opening S11 the dry mode valve 5 may have a variable duration. For example, the duration may be 1 minute, or 2 minutes, or 5 minutes, or 10 minutes. Opening S13 the recirculation valve 11 permits the air of the first flow F1 to be diverted to the second flow F2. As such, the air of the first flow F1 is exhausted from the system 1. Condensate in the air-to-air heat exchanger 2 on the side of the first flow F1 will then be evacuated due to the flow and pressure of the air from the first flow F1 that is diverted to the second flow F2.
In some embodiments, heating S12 is performed. During heating S12, the air of the first flow F1 is heated by a heater 8. The heater 8 may e.g. be arranged in a air conditioning unit 7. Thus, when the air is recirculated and passed through the air-to-air heat exchanger 2, the air-to-air heat exchanger 2 is heated up. As such, the transfer of condensate is further facilitated by evaporation due to the increased temperature of the air-to-air heat exchanger 2.

Claims

C L A I M S
1. Cabin air heat recovery system for an electrical vehicle comprising: an air-to-air heat exchanger adapted to transfer heat between a first flow to be supplied to the cabin of the electrical vehicle and a second flow to be exhausted from a cabin of the electrical vehicle; at least one sensor for measuring a first input parameter from the air- to-air heat exchanger or air of the second flow; a recirculation valve for recirculating a volume of air of the second flow to the first flow, wherein said recirculation valve is adapted to recirculate said volume of air of the second flow to the first flow upstream of said air- to-air heat exchanger, or for diverting a volume of air of the first flow to the second flow, wherein said recirculation valve is adapted to divert said volume of air of the first flow to the second flow upstream of said air-to-air heat exchanger; and a control unit configured to control the recirculation valve and thereby the volume of air of the second flow to be recirculated to the first flow based on said first input parameter or the volume of air of the first flow to be diverted to the second flow based on said first input parameter.
2. The cabin air heat recovery system according to claim 1 , wherein said first input parameter is a temperature value measured by at least one temperature sensor.
3. The cabin air heat recovery system according to claim 2, wherein said at least one temperature sensor is arranged in the second flow downstream the air-to-air heat exchanger.
4. The cabin air heat recovery system according to claim 1 , wherein said first input parameter is a humidity level of the second flow measured by a humidity sensor.
5. The cabin air heat recovery system according to claim 1 , wherein said first input parameter is a CO2 level of the second flow measured by a CO2 sensor.
6. The cabin air heat recovery system according to claim 1 , the system comprising a first sensor for measuring a first input parameter and a second sensor for measuring a second input parameter.
7. The cabin air heat recovery system according to claim 6, wherein said first input parameter is a temperature value measured by at least one temperature sensor and wherein said second input parameter is a humidity of the second flow measured by a humidity sensor.
8. The cabin air energy reuse system according to any preceding claim, further comprising an auxiliary heater and/or a cooler.
9. The cabin air energy reuse system according to claim 8, further comprising a dry mode valve adapted to recirculate at least a part of said first flow downstream of the air-to-air heat exchanger via the auxiliary heater and to said first flow upstream of the air-to-air heat exchanger.
10. The cabin air energy reuse system according to any preceding claims, wherein said air-to-air heat exchanger comprises a plurality of channels and wherein said recirculation valve is adapted to control the flow of the first volume of the second flow to at least one of said plurality of channels based on said first and/or second input parameter.
11. Method for operating an air-to-air heat exchanger in a cabin air heat recovery system according to claim 1, the method comprising: measuring a first temperature T1 of the air-to-air heat exchanger or the air of the second flow with at least one temperature sensor; and if T1 is equal to or below a predetermined temperature threshold value, opening the recirculation valve such that at least a part of the second flow is recirculated to the first flow.
12. The method according to claim 11 , further comprising: measuring a temperature T2 of at least one of a plurality of channels of said air-to-air heat exchanger; and directing the at least part of the second flow to said at least one of a plurality of channels if the temperature T2 is below said predetermined value.
13. The method according to any one of claims 11-12, further comprising: measuring a first humidity level H1 of the second flow with a humidity sensor, and wherein the amount of the second flow to be recirculated to the first flow by the recirculation valve is determined by said first humidity level.
14. The method according to any one of claims 11-13, said method further comprising evacuating condensate by: after performing the steps in any one of claims 11-13, closing the recirculation valve; opening a dry mode valve such that at least a part of said first flow downstream of the air-to-air heat exchanger is recirculated to said first flow upstream of the air-to-air heat exchanger; and opening the recirculation valve such that part of the first flow is diverted to the second flow.
15. The method according to claim 14, further comprising: heating the first flow with an auxiliary heater.
PCT/EP2022/055554 2021-03-05 2022-03-04 Hvac heat recovery system WO2022184894A1 (en)

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SE2150255 2021-03-05

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013184691A (en) * 2012-03-12 2013-09-19 Panasonic Corp Vehicle air-conditioning device
JP2013189043A (en) * 2012-03-13 2013-09-26 Panasonic Corp Air conditioning device for vehicle
JP2013203196A (en) * 2012-03-28 2013-10-07 Panasonic Corp Air conditioner for vehicle
US20150118946A1 (en) * 2013-10-30 2015-04-30 Hyundai Motor Company Automobile Ventilation Method

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013184691A (en) * 2012-03-12 2013-09-19 Panasonic Corp Vehicle air-conditioning device
JP2013189043A (en) * 2012-03-13 2013-09-26 Panasonic Corp Air conditioning device for vehicle
JP2013203196A (en) * 2012-03-28 2013-10-07 Panasonic Corp Air conditioner for vehicle
US20150118946A1 (en) * 2013-10-30 2015-04-30 Hyundai Motor Company Automobile Ventilation Method

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