WO2023037897A1

WO2023037897A1 - Vehicle heating, ventilation, air conditioning system and method for dehumidification and reheat of cabin air using the same

Info

Publication number: WO2023037897A1
Application number: PCT/JP2022/032140
Authority: WO
Inventors: Patrick Horn; Shivakumar Banakar; Dennis Wleklik; Ariel Marasigan
Original assignee: Denso Corporation; Denso Automotive Deutschland Gmbh
Priority date: 2021-09-08
Filing date: 2022-08-26
Publication date: 2023-03-16
Also published as: DE102021123257A1

Abstract

A vehicle HVAC system and a method for dehumidification and reheat of cabin air is provided, avoiding electric heaters for cabin air heating and dehumidification. A control system (30) of the vehicle HVAC system with a heat pump arrangement (2) and a hot gas bypass (26) is configured to, based upon at least an ambient temperature and a cabin temperature, control the heat pump arrangement to operate in one of an efficient mode or in an inefficient mode. In the inefficient mode, part of a compressed refrigerant gas at a compressor outlet is fed back to a chiller inlet via the hot gas bypass. A compressor (4) generates a greater amount of heat in the inefficient mode than in the efficient mode. As a result, the vehicle HVAC system provides sufficient heat for heating of cabin air.

Description

VEHICLE HEATING, VENTILATION, AIR CONDITIONING SYSTEM AND METHOD FOR DEHUMIDIFICATION AND REHEAT OF CABIN AIR USING THE SAME

Cross Reference

This application claims the benefit of DE Patent Application No. 10 2021 123 257.0, filed on September 8, 2021. The entire disclosures of the above application is incorporated herein by reference.

The disclosure relates to a vehicle heating, ventilation, air conditioning system and to a method for dehumidification and reheat of cabin air using the same.

The lack of waste heat from battery electric vehicles requires additional heat sources to satisfy cabin heating and comfort demands. The lack of heating performance is typically compensated by an electric heater. An additional electric heater may result in packaging challenges and also cost up of thermal management systems.

From PLT1, using the compressor as heat source for heating the passenger cabin. However, there may be still the need for a low voltage heater for heating the cabin air.

US2019/0070924A1

Summary

As well known in the art vehicle heating, ventilation, air conditioning systems typically comprise a refrigerant cycle arrangement. Such refrigerant cycle arrangement comprises in fluid direction a compressor, a high-pressure heat exchanger (typically a condenser), an expansion valve, a low-pressure heat exchanger (such as an evaporator and/or chiller), looping back to the compressor. As well known in the art, an outer heat exchanger may be configured as high-pressure, medium-pressure or low-pressure heat exchanger depending on the operation mode.

The heat pump arrangement as essential part of the vehicle heating, ventilation, air conditioning system must fulfil the complete range of operation in most efficient way to maximise both climate comfort and range of BEV, i.e., a battery electric vehicle. This means that dehumidification of cabin must be possible when required.

Also switching to this mode and from this mode to other modes should not be noticeable for the end customer. As should be appreciated in the context of the present disclosure, next to dehumidification mode, other modes particularly comprise a heating mode and a cooling mode (AC mode) with the pressure level of the outer heat exchanger being controlled such to either harvest thermal energy from the environment or to dispose excess heat.

It is an object of the disclosure to provide a vehicle heating, ventilation, air conditioning system that avoids electric heaters for cabin air heating and dehumidification.

It is further an object to provide a method for dehumidification and reheat of cabin air with such a vehicle heating, ventilation, air conditioning system.

These objects are solved with a vehicle heating, ventilation, air conditioning system according to corresponding claims and with a method according to corresponding claims.

The control system of the vehicle heating, ventilation, air conditioning system with a heat pump arrangement and a hot gas bypass is configured to, based upon at least an ambient temperature and a cabin temperature, control the heat pump arrangement to operate in one of an efficient mode or in an inefficient mode, wherein in the inefficient mode part of the compressed refrigerant gas at the compressor outlet is fed back to the chiller inlet via the hot gas bypass so that the compressor generates a greater amount of heat in the inefficient mode than in the efficient mode and thereby provides sufficient heat for heating of cabin air.

In a preferred embodiment, the heat output of the cabin condenser is increased by coupling waste heat from the vehicle or ambient heat via a coolant circuit into the chiller.

In a preferred embodiment, an expansion valve between the cabin condenser for cabin heating and the outside heat exchanger is provided in order to operate the outside heat exchanger as a condenser on lower refrigerant pressure level and thus at a lower refrigerant condensation temperature level. Thus the heat rejection by the outside heat exchanger is reduced and more heat output of the cabin condenser is available. For high cabin heating demands, the heat rejection to the ambient through the outside heat exchanger must be lowered. Completely bypassing or switching off the outside heat exchanger is not possible since this would result in too much heat output at the cabin condenser. Therefore, the heat rejection via the outer heat exchanger has to be minimized as much as possible while the system is operated in an inefficient mode at the same time to increase the load of the compressor in order to increase the heating performance via the hot gas bypass.

In a preferred embodiment, waste heat rejected by the outside heat exchanger is partly recovered with a waste heat loop including a gas/liquid heat exchanger positioned in the vicinity of the outer heat exchanger and coupled into the chiller to increase the heat output of the cabin condenser. This recovering of heat from the outside heat exchanger is applicable with or without use of the compressor bypass.

Preferably the gas/liquid heat exchanger is positioned ambient air downstream to the outer heat exchanger.

Fig. 1 illustrates a first embodiment of the disclosure applying a hot gas bypass to decrease the efficiency of the heat pump arrangement such that heat output of the cabin condenser can be increased. Fig. 2 illustrates a second embodiment of the disclosure applying a coolant circuit recovering heat rejected from the outer heat exchanger and coupling it into the chiller.

In the following preferred embodiments of the disclosure are described with reference to the drawing. A vehicle heating, ventilation, air conditioning system may be referred to as a vehicle HVAC system.

Fig. 1 illustrates a first embodiment of the disclosure with a heat pump cycle arrangement comprising in fluid direction with a compressor 4, condenser 6, outer heat exchanger 12, chiller expansion valve 18 and chiller 10, back to compressor 4.

In more detail, the heat pump arrangement 2 comprises a compressor 4 with a compressor inlet 4-i and a compressor outlet 4-o, a cabin condenser 6 with a condenser inlet 6-i and a condenser outlet 6-o, a cabin evaporator 8 with an evaporator inlet 8-i and an evaporator outlet 8-o, a chiller 10 with a chiller inlet 10-I and a chiller outlet 10-o and an outer heat exchanger 12 with an outer heat exchanger inlet 12-I and an outer heat exchanger outlet 12-o. The outer heat exchanger outlet 12-o is connected to a refrigerant reservoir 14 having a reservoir inlet 14-I and a reservoir outlet 14-o via a valve device 16.

The reservoir outlet is connected in parallel to a chiller expansion valve 18 at the chiller inlet 10-i and to evaporator expansion valve 22 at the evaporator inlet 8-1. The evaporator outlet 8-o is connected to the compressor inlet 4-i via a check valve 23. Between the condenser outlet 6-o and the outer heat exchanger inlet 12-i an expansion valve device 24 is provided. Between the chiller inlet 10-i and the compressor outlet 4-o a compressor bypass 26 is arranged including a bypass expansion valve 28.

The whole heat pump arrangement 2 is controlled by a control system 30. The control system 30 also controls the components of the vehicle HVAC system. The control system 30 at least includes a processor which performs control processing of the heat pump arrangement 2, such as control of opening degree of the expansion valve device 24. Preferably, the control system 30 further includes a computer readable non-transitory storage medium, e.g., a semiconductor memory device, to store computer readable instructions which, when executed by the processor, makes the processor to perform the controls.

The control system 30 includes sensors to monitor behavior, temperature and/or pressure, of the vehicle HVAC system. The sensors at least including an ambient temperature sensor to provide data indicative of an ambient temperature, and a cabin temperature sensor to provide data indicative of a cabin temperature. The sensors may include pressure and/or temperature sensors of the refrigerant. The sensors may include a pressure and/or temperature sensor of the refrigerant in the cabin condenser 6 and/or the outer heat exchanger 12 to provide data indicative of a pressure and/or temperature of the refrigerant. The control system 30, by a processor, monitors those data provided by the sensors and controls components of the vehicle HVAC system to perform method described in this specification. For example, the control system 30 controls the expansion valve 24 to operate the cabin condenser 6 on a higher pressure/temperature level than the outer heat exchanger 12.

Dehumidification with the cabin condenser 6 and the outer heat exchanger 12 being operated on the high pressures side of the system is called series dehumidification. When heating performance during series dehumidification is insufficient, the outside heat exchanger 12 must be controlled to a lower pressure level by means of the heat expansion valve 24 to reduce heat losses to the ambient.

If this is not enough, an additional heat source in the form of waste heat from the compressor 4 is added with the heat pump arrangement is operated in an inefficient mode. In this inefficient mode, part of the compressed refrigerant gas at the compressor outlet 4-o is led to the chiller inlet 10-i via the compressor bypass 26 with bypass expansion valve 28 in order to increase the refrigerant mass flow rate of the compressor 4 which in turn causes a higher load on the compressor 4 to be used for heating the vehicle cabin.

Fig. 2 illustrates a second embodiment that differs from the first embodiment in that the expansion valve 24 is omitted, there is only a shut valve 40, and the compressor bypass 26 is omitted. Since there is no heat split-up expansion valve 24, the heat rejection of the outer heat exchanger 12 to the ambient cannot be controlled and cannot be reduced.

There is provided a waste heat loop 42 connecting a gas/liquid heat exchanger 44 with a coolant circuit and a coolant pump 48 to the chiller 10. The gas/liquid heat exchanger 44 is positioned adjacent the outer heat exchanger 12 downstream of ambient air picking up heat rejected by the outer heat exchanger 12. Thus, the waste heat loop 42 partly recovers the heat rejected by the outer heat exchanger 12 couple it into chiller 10 and is thus additional heat output by cabin condenser 6 to heat and dehumidify the cabin air.

Although the compressor bypass 26, i.e., the hot gas bypass, and the bypass expansion valve 28 are omitted in Fig. 2, the heat pump arrangement 2 in the second embodiment include the compressor bypass 26, i.e., the hot gas bypass and the bypass expansion valve 28. The control system 30 in the second embodiment may activate the hot gas bypass in order to increase heat for cabin heating.

The waste heat loop 42 provides a coolant circuit which is provided to pick up waste heat from vehicle components and/or ambient heat and feed it into the chiller 10. The waste heat loop 42 may be combined with the first embodiment shown in FIG. 1. In this case, the control system 30, by the processor, performs a first cabin heat mode by activating the heat pump cycle, and a second cabin heat mode by activating both the heat pump cycle and the waste heat loop 42. The control system 30, by the processor, further performs a third cabin heat mode by activating the hot gas bypass 26 in addition to the first cabin heat mode or the second cabin heat mode. The third cabin heat mode may be performed instead of the second cabin heat mode, or may be performed in addition to the first and second cabin heat mode.

In this embodiment, the control system 30 performs control for components of the heat pump arrangement 2. For example, the control system 30 activates the coolant pump 48 to activate the waste heat loop 42, and the control system 30 deactivates the coolant pump 48 to deactivate the waste heat loop 42. Further, the control system 30 varies a capacity of the coolant pump 48 to vary a heat recovering amount by the waste heat loop 42.

The embodiments disclosed in this specification provide sufficient disclosure for the following technical concepts 1 to 10.

Technical concept 1 is a vehicle heating, ventilation, air conditioning system comprising: a heat pump arrangement (2) including a compressor (4) with a compressor inlet (4-i) and outlet (4-o), a cabin condenser (6) with a condenser inlet (6-i) and outlet (6-o), an outer heat exchanger (12) with an outer heat exchanger inlet (12-i) and outlet (12-o), a chiller expansion valve (18) and a chiller (10) with a chiller inlet (10-i) and outlet (10-o); a hot gas bypass (26) between a compressor outlet (4-o) and the chiller inlet (10-i), comprising a bypass expansion valve (28); a control system (30) configured to, based upon at least an ambient temperature and a cabin temperature, control the heat pump arrangement (2) to operate in one of an efficient mode or in an inefficient mode, wherein in the inefficient mode, part of a compressed refrigerant gas at the compressor outlet (4-o) is fed back to the chiller inlet (10-i) via the hot gas bypass (26) so that the compressor (4) generates a greater amount of heat in the inefficient mode than in the efficient mode and thereby provide sufficient heat for cabin heating.

Technical concept 2 is the vehicle heating, ventilation, air conditioning system of the technical concept 1, wherein the compressor (4), condenser (6), outer heat exchanger (12), chiller expansion valve (18) and chiller (10), back to compressor (4) are arranged in fluid direction in a cycle arrangement.

Technical concept 3 is the vehicle heating, ventilation, air conditioning system of the technical concept 1 or 2, wherein a coolant circuit (42) is provided to pick up waste heat from vehicle components (12) and/or ambient heat and feed it into the chiller (10).

Technical concept 4 is the vehicle heat ventilating and air conditioning system of any one of the technical concept 1-3, wherein an expansion valve (24) is provided between the cabin condenser (6) and the outer heat exchanger (12).

Technical concept 5 is the vehicle heating, ventilation, air conditioning system of the technical concept 3, wherein the coolant circuit (42) comprises a gas/liquid heat exchanger (44) to couple heat rejected from the outer heat exchanger (12) into the chiller (10).

Technical concept 6 is the vehicle heating, ventilation, air conditioning system of the technical concept 5, wherein the gas/liquid heat exchanger (44) is provided in the vicinity of the outer heat exchanger (12) with an ambient air stream being guided from the outer heat exchanger (12) to the gas/liquid heat exchanger (44).

Technical concept 7 is a method for dehumidification and reheat of cabin air with a vehicle heating, ventilation, air conditioning system of any one of the technical concepts 1-6, wherein both the cabin condenser (6) and the outer heat exchanger (12) are operated to discharge heat, and wherein part of the compressed refrigerant gas at the compressor outlet (4-o) is fed back to the chiller inlet (10-i) via the hot gas bypass (26) so that heat pump arrangement (2) operates in an inefficient mode, to thereby provide sufficient heat output of the cabin condenser (6) for heating of cabin air.

Technical concept 8 is the method of the technical concept 7, wherein a waste heat from vehicle components (12) and/or ambient heat is coupled into the chiller (10).

Technical concept 9 is the method of the technical concept 7 or 8, wherein the cabin condenser (6) is operated on a higher pressure/temperature level than the outer heat exchanger (12) by means of expansion valve (24).

Technical concept 10 is the method of any one of the technical concepts 7-9, wherein heat discharged from the outer heat exchanger (12) is coupled into chiller (10) to increase the heat output of the cabin condenser (6).

2 heat pump arrangement
4 compressor
4-i compressor inlet
4-o compressor outlet
6 cabin condenser
6-i condenser inlet
6-o condenser outlet
8 cabin evaporator
8-i evaporator inlet
8-o evaporator outlet
10 chiller
10-i chiller inlet
10-o chiller outlet
12 outer heat exchanger
12-i outer heat exchanger inlet
12-o outer heat exchanger outlet
14 refrigerant reservoir
14-i reservoir inlet
14-o reservoir outlet
16 valve device
18 chiller expansion valve
20 evaporator expansion valve
22 expansion valve
23 check valve
24 expansion valve
26 hot gas bypass
28 bypass expansion valve
30 control system
40 shut valve
42 coolant circuit
44 gas/liquid heat exchanger
48 coolant pump

Claims

A vehicle heating, ventilation, air conditioning system, comprising:
a heat pump arrangement (2) including a compressor (4) with a compressor inlet (4-i) and outlet (4-o), a cabin condenser (6) with a condenser inlet (6-i) and outlet (6-o), an outer heat exchanger (12) with an outer heat exchanger inlet (12-i) and outlet (12-o), a chiller expansion valve (18) and a chiller (10) with a chiller inlet (10-i) and outlet (10-o);
a hot gas bypass (26) between a compressor outlet (4-o) and the chiller inlet (10-i), comprising a bypass expansion valve (28);
a control system (30) configured to, based upon at least an ambient temperature and a cabin temperature, control the heat pump arrangement (2) to operate in one of an efficient mode or in an inefficient mode, wherein in the inefficient mode, part of a compressed refrigerant gas at the compressor outlet (4-o) is fed back to the chiller inlet (10-i) via the hot gas bypass (26) so that the compressor (4) generates a greater amount of heat in the inefficient mode than in the efficient mode and thereby provide sufficient heat for cabin heating.
The vehicle heating, ventilation, air conditioning system of claim 1,
wherein the compressor (4), condenser (6), outer heat exchanger (12), chiller expansion valve (18) and chiller (10), back to compressor (4) are arranged in fluid direction in a cycle arrangement.
The vehicle heating, ventilation, air conditioning system of claim 1 or 2,
wherein a coolant circuit (42) is provided to pick up waste heat from vehicle components (12) and/or ambient heat and feed it into the chiller (10).
The vehicle heating, ventilation, air conditioning system of any one of claims 1-3,
wherein an expansion valve (24) is provided between the cabin condenser (6) and the outer heat exchanger (12).
The vehicle heating, ventilation, air conditioning system of claim 3,
wherein the coolant circuit (42) comprises a gas/liquid heat exchanger (44) to couple heat rejected from the outer heat exchanger (12) into the chiller (10).
The vehicle heating, ventilation, air conditioning system of claim 5,
wherein the gas/liquid heat exchanger (44) is provided in the vicinity of the outer heat exchanger (12) with an ambient air stream being guided from the outer heat exchanger (12) to the gas/liquid heat exchanger (44).
A method for dehumidification and reheat of cabin air with a vehicle heating, ventilation, air conditioning system of any one of claims 1-6,
wherein both the cabin condenser (6) and the outer heat exchanger (12) are operated to discharge heat, and
wherein part of the compressed refrigerant gas at the compressor outlet (4-o) is fed back to the chiller inlet (10-i) via the hot gas bypass (26) so that heat pump arrangement (2) operates in an inefficient mode, to thereby provide sufficient heat output of the cabin condenser (6) for heating of cabin air.
The method of claim 7,
wherein a waste heat from vehicle components (12) and/or ambient heat is coupled into the chiller (10).
The method of claim 7 or 8,
wherein the cabin condenser (6) is operated on a higher pressure/temperature level than the outer heat exchanger (12) by means of expansion valve (24).
The method of any one of claims 7-9,
wherein heat discharged from the outer heat exchanger (12) is coupled into chiller (10) to increase the heat output of the cabin condenser (6).