Phase change material evaporator charging control

Patent metadata

Field	Value
Publication number	US-9464837-B2
Application number	US-201313930322-A
Country	US
Kind code	B2
Filing date	Jun 28, 2013
Priority date	Mar 21, 2012
Publication date	Oct 11, 2016
Grant date	Oct 11, 2016

Abstract

A method of controlling an air conditioning compressor in a heating ventilation and air conditioning system having a evaporator including a phase change material is presented. The method includes the steps of measuring an evaporator output air temperature, determining a state of charge value by calculating a difference between an estimated refrigerant temperature based on the evaporator output air temperature and a phase change material freeze temperature and integrating this difference over time and operating the air conditioning compressor to maintain the state of charge value between an upper and lower limit. A method of recovering braking energy in a vehicle containing a heating ventilation and air conditioning system having the evaporator including the phase change material is also presented.

First claim

We claim:

1. A method of controlling an air conditioning (A/C) compressor in a heating ventilation and air conditioning (HVAC) system having an evaporator including a phase change material, the method comprising the steps of:
measuring an evaporator output air temperature (EOAT);
determining a state of charge (SoC) value based on the EOAT;
determining an upper limit value and a lower limit value for the SoC;
initiating operation of the A/C compressor when the SoC value is less than or equal to the lower limit value; and
discontinuing operation of the A/C compressor when the SoC value is greater than or equal to the upper limit value.

2. The method according to claim 1 , further comprising the steps of:
determining whether the HVAC system is operating in a defog mode; and
operating the A/C compressor according to a freeze control method when the HVAC system is operating in the defog mode.

3. The method according to claim 1 , further comprising the steps of:
determining a humidity value within a vehicle cabin; and
operating the A/C compressor according to a freeze method when the humidity value exceeds a threshold.

4. The method according to claim 1 , further comprising the step of:
determining an outside ambient air temperature, wherein the upper limit value is based on the outside ambient air temperature.

5. The method according to claim 1 , further comprising the step of:
determining an average vehicle stop time, wherein the lower limit value is based on the average vehicle stop time.

6. The method according to claim 1 , further comprising the step of:
providing the evaporator that includes the phase change material.

7. The method according to claim 1 , further comprising the steps of:
providing a variable displacement A/C compressor; and
operating the A/C compressor in full displacement mode.

8. The method according to claim 1 , wherein a mass of phase change material in the evaporator is Mss+Ma, where Mss is a phase change material mass required for start-stop operation and Ma is an additional phase change material mass and wherein the lower limit value is Mss/(Mss+Ma).

9. The method according to claim 1 , wherein the step of determining the state of charge (SoC) value further includes the steps of:
determining the SoC value by calculating a difference between an estimated refrigerant temperature based on the EOAT and a phase change material freeze temperature and integrating the difference over time; and
applying a calibratable factor to the SoC value so that the SoC value indicates a percentage of phase change material charged.

10. The method according to claim 9 , further comprising the steps of:
initializing the SoC value to zero after a prolonged calibratable period of HVAC system off time; and
truncating the value of the SoC value to 1 (100%) when the SoC value is greater than 1 (100%).

11. A method of recovering braking energy in a vehicle having a HVAC system having the evaporator including the phase change material, the method comprising the steps of:
converting a portion of the vehicle's kinetic energy to mechanical energy;
providing a portion of the mechanical energy to an A/C compressor;
operating the A/C compressor to compress a refrigerant to a liquid state;
evaporating the refrigerant to a gaseous state within the evaporator, thereby changing a liquid state of the phase change material to a solid state and thereby storing energy from the A/C compressor, wherein the A/C compressor is controlled by the method of claim 1 .

12. The method according to claim 11 , further comprising the steps of:
converting a portion of the mechanical energy to electrical energy; and
providing a portion of the electrical energy to an electrical motor driving the A/C compressor.

13. A method of recovering braking energy in a vehicle having a HVAC system having an evaporator including a phase change material, the vehicle having a kinetic energy, the method comprising the steps of:
converting a portion of the vehicle's kinetic energy to mechanical energy;
providing a portion of the mechanical energy to an A/C compressor;
operating the A/C compressor to compress a refrigerant to a liquid state;
evaporating the refrigerant to a gaseous state within the evaporator, thereby changing a liquid state of the phase change material to a solid state and thereby storing energy from the A/C compressor.

14. The method according to claim 13 , further comprising the steps of:
converting a portion of the mechanical energy to electrical energy; and
providing a portion of the electrical energy to an electrical motor driving the A/C compressor.

15. The method according to claim 13 , further comprising the steps of:
detecting whether the vehicle is driving downhill;
determining a downhill driving time period;
operating the A/C compressor according to sub-freeze control when the downhill driving time is within the downhill driving time period; and
operating the A/C compressor according to standard freeze control when the downhill driving time period is exceeded.

16. The method according to claim 13 , further comprising the steps of:
detecting whether the vehicle is decelerating;
determining a deceleration time period; and
operating the A/C compressor according to sub-freeze control when the deceleration time is within the deceleration time period; and
operating the A/C compressor according to standard freeze control when the deceleration time period is exceeded.

17. A method of controlling an A/C compressor in a HVAC system having an evaporator including a phase change material, the method comprising the steps of:
determining an increased engine load;
determining an increased engine load time period; and
discontinuing operation of the A/C compressor until the increased engine load time period exceeds a threshold; and
operating the A/C compressor according to a Series Reheat Reduction (SRR) method when the increased engine load time period exceeds the threshold.

18. The method according to claim 17 , further comprising the steps of:
detecting whether the vehicle is driving uphill;
determining an uphill driving time period;
operating the A/C compressor according to the SRR method control when the downhill driving time is within the downhill driving time period; and
operating the A/C compressor according to standard freeze control when the PCM charge is below a SoC threshold.

19. The method according to claim 17 , further comprising the steps of:
detecting whether the vehicle is accelerating;
determining an acceleration time period; and
operating the A/C compressor according to the SRR method when the acceleration time exceeds the acceleration time period; and
operating the A/C compressor according to standard freeze control when the PCM charge is near a low threshold.

Assignees

• Mahle Int Gmbh

Inventors

• Wang Mingyu
• Kadle Prasad S
• Wolfe Iv Edward

Classifications

• F25B2400/24

  Thermal storage element · CPC title

• F28D1/0341

  with U-flow or serpentine-flow inside the conduits · CPC title

• F25B49/022 Primary

  Compressor control arrangements · CPC title

• F28F21/08

  of metal · CPC title

• F28D2020/0013

  the heat storage material being enclosed in elements attached to or integral with heat exchange conduits · CPC title