Binary Working Fluid Air Conditioning System

This invention relates to an air conditioning system for vehicles.

The U.S. Pat. Nos. to Baker, 3,228,189; Andrews, 3,252,298; Johnson, 3,350,876; Balje et al, 3,713,294; Morgan et al, 3,830,062; Edwards, 3,968,649 and Milling, 4,069,672 disclose waste heat recovery systems for internal combustion engines. The U.S. Pat. No. to Edwards, 3,967,466 discloses an air and waste vapor reverse Brayton cycle air conditioning system.

According to this invention a condensible working fluid is used to extract waste heat from the engine exhaust, hot engine oil or other engine waste heat sources of an internal combustion engine to drive a turbine. The turbine is used to drive a reverse Brayton cycle cooling system. The superheated working fluid is expanded down to a lower temperature and pressure in the turbine and is then supplied to the output of the compressor of the reverse Brayton cycle cooling system. The return from the turbine and the output of the compressor is then passed through a heat rejection heat exchanger where the excess water vapor is condensed and returned to the waste heat recovery system.

FIG. 1 is a schematic diagram, partially in block form showing a reverse Brayton cycle cooling system with a turbine drive according to the invention.

FIG. 2 is a block diagram showing one possible waste heat recovery system which can be used in the device of FIG. 1.

FIG. 3 shows a pressure-enthalpy refrigeration cycle diagram for the device of FIG. 1.

FIG. 4 shows a pressure-enthalpy power cycle diagram for the device of FIG. 1.

Reference is now made to FIG. 1 of the drawing which shows a conventional reverse Brayton cycle cooling system 10 having a housing 12 including a chamber 14. The cooling system includes a compressor and an expander driven by a common shaft 16. The compressor and expander include a sliding vane rotor 18 positioned within chamber 14 with a compressor section 20 on one side of the rotor and an expander section 22 on the other side of the rotor.

Air from the heat exchanger 24, which supplies cooling for the passenger compartment of a vehicle, is supplied to the compressor inlet 26. The compressed air at outlet 28 is supplied to a heat rejection heat exchanger 30 which would normally be air cooled. The output of the heat exchanger 30 is supplied to the expander section 22 through inlet 32. The cooled air at the outlet 34 is supplied to the heat exchanger 24 as in a conventional reverse Brayton cycle cooling system which runs on a conventional reverse Brayton cycle as shown in the pressure-enthalpy diagram in FIG. 3.

The rotor 18 is driven by a turbine 36 having a sliding vane rotor 38 within a chamber 40 and connected to shaft 16. The chamber 40 can be located within housing 12 with a wall, not shown, separating chambers 14 and 40. The shaft 16 would pass through the wall between chambers 14 and 40 with seals, not shown, provided as required. For some applications separate housings for the cooling system and the drive turbine may be desired. Also other low speed turbines than that shown could be used.

The turbine is driven by superheated steam from a waste recovery system 44. Water condensed in heat exchanger 30 is pumped into the waste heat recovery system 44 by a pump 46. Superheated steam from the waste heat recovery system 44 is supplied to inlets 48 and 50 of the turbine 36. The output, from turbine outlets 52 and 54, is mixed with the output 28 of compressor 20 and supplied to the heat exchanger 30. The saturated steam from the turbine is added to the unsaturated air at the output of the compressor and the combination passes through the heat exchanger 30 wherein the excess water vapor is condensed with the condensate collecting in the heat exchanger. The water in the heat exchanger is returned to the waste heat recovery system 44 by pump 46.

The waste heat recovery system 44 includes one or more heat exchangers shown in FIG. 2. The water from pump 46 is supplied to an oil cooler heat exchanger 50 and then to an engine cooler heat exchanger 52, which can be the water jacket of the engine. The water from heat exchanger is converted to superheated steam in the exhaust gas heat exchanger 54. The steam leaving the exhaust gas heat exchanger can be raised to a higher temperature in the catalitic converter heat exchanger 56 before application to the turbine 36. While water and air have been described as the working fluids, other combinations of condensible and non-condensible working fluids can be used for certain applications. For the purpose of this application, a condensible working fluid is defined as a fluid which will change its phase from gas to liquid and vice versa within the temperature and pressure ranges of 100.degree. F. to 450.degree. F. and 1 psia to 450 psia, respectively. A non-condensible working fluid remains a gas over the same temperature and pressure range.

The operation of the cooling system 10 is the same as conventional reverse Brayton cycle cooling systems such as described in the U.S. Pat. No. to Edwards, 3,967,466 and as indicated in FIG. 3. With water added as in Edwards, vapor saturated air, at inlet 26 is no longer saturated after being compressed in compressor section 20. The steam from the turbine mixes with the water at the inlet to the heat rejection heat exchanger and is removed as condensate in the heat exchanger 30 and returned to the waste heat recovery system 44 by the pump 46. The turbine drives the rotor 18 through shaft 16. The power cycle is shown in the pressure-enthalpy diagram in FIG. 4 wherein leg AB represents action of pump 46; leg BC represents the heat addition phase in the waste heat recovery system 44; CD' represents the turbine phase; D'D represents any losses in the line from the turbine to the heat exchanger 30 and DA represents the heat rejection phase.

There is thus provided an air conditioning system for vehicles which makes use of waste heat.