VEHICLE AIR CONDITIONING SYSTEM

Abstract

A vehicle air-conditioning system includes at least one chiller and one cold storage unit which is designed as a PCM storage system with phase change material. The refrigeration power required for air-conditioning and for charging the PCM storage system are provided by the chiller where the cold stored in the PCM storage system is supplied to the assemblies for air-conditioning the passenger compartment in selected operating states of the vehicle. A sufficiently large amount of cold can be conducted from a phase change material of the PCM storage system into the passenger compartment such that the chiller of the air conditioning system designed for cold generation is largely put out of operation and the discharge of larger amounts of heat from the rail vehicle into the tunnel is thereby avoided.

Claims

1. A vehicle air-conditioning system comprising: at least one chiller; a phase change material (PCM) storage system having at least one cold storage unit with a phase change material, wherein the at least one chiller is configured to provide first refrigeration power for air-conditioning a vehicle passenger compartment and to provide second refrigeration power for charging the PCM storage system, the PCM storage system configured to supply cold energy to one or more vehicle assemblies configured to air condition the vehicle passenger compartment in selected operating states of a vehicle, the PCM storage system having a primary circuit with a refrigerant and a secondary circuit with a water-glycol mixture and a water heat exchanger, the at least one chiller arranged in the primary circuit, the PCM storage system including a plate heat exchanger between the primary circuit and the secondary circuit, the PCM storage system and the water heat exchanger of the secondary circuit arranged one after another in a direction of flow in the secondary circuit, the phase change material arranged in a form of plate-shaped segments in a container of the PCM storage system, the secondary circuit configured to direct flow of the water-glycol mixture around the phase change material in the container; and a bypass line arranged respectively at the PCM storage system and at the water heat exchanger in the secondary circuit, the bypass line configured to be opened or shut off by a three-way valve as a function of an operating mode of the vehicle air-conditioning system.

2. A method for operating the vehicle air-conditioning system according to claim 1, comprising: charging the PCM storage system with the cold energy during operation of the vehicle while traveling outside a tunnel; and feeding the cold energy storage in the PCM storage system to the water heat exchanger while the at least one chiller is not in operation.

3. The method of claim 2, wherein charging the PCT storage system with the cold energy by the at least one chiller also includes providing the cold energy for cooling the passenger compartment during operation of the vehicle while traveling outside of the tunnel.

4. The method of claim 3, further comprising: adjusting a percentage ratio of charging or provision of the cold energy for the PCM storage system and for the passenger compartment.

5. The method of claim 2, wherein charging the PCM storage system includes initially only charging the PCT storage system with the cold energy after the PCM storage system has been fully charged.

Description

DESCRIPTION OF THE DRAWINGS

[0026] In the following, an embodiment example of the invention is explained in more detail. Herein,

[0027] FIG. 1 shows the basic structure of an air-conditioning system for a rail vehicle designed according to the invention with a PCM storage system as the cold storage unit.

DETAILED DESCRIPTION

[0028] The air conditioning system shown in stylized form in FIG. 1 is designed for a rail vehicle and comprises a chiller 1 and a cold storage unit 12. The cold storage unit 12 is designed as a PCM storage system with phase change material. The chiller 1 provides the refrigeration power required for air conditioning the passenger compartment (not shown) and the refrigeration power required for charging the PCM storage system 12. The cold stored in the PCM storage system 12 is supplied to the assemblies for air conditioning the passenger compartment in selected operating states of the rail vehicle—preferentially during travel in a tunnel.

[0029] It can be seen from the drawing that the cooling circuit is divided into a primary circuit (TOP) with a refrigerant and a secondary circuit (BELOW) with a water-glycol mixture. All available refrigerants are suitable as refrigerants for the primary circuit, which is to say both synthetic (for example, R134a) and natural (for example, CO.sub.2 or propane) refrigerants.

[0030] The primary circuit with the chiller 1, a condenser 2 and an expansion valve 9 provides the refrigeration power for air conditioning the passenger compartment and for charging the PCM storage system 12.

[0031] For this purpose, the refrigeration power is transferred from the primary circuit to the secondary circuit via a plate heat exchanger 10. In this secondary circuit, the PCM storage system 12 and a water heat exchanger 3 for cooling the air in the passenger compartment are arranged one after the other in the direction of flow from the plate heat exchanger 10. A water pump 11 is arranged downstream of the water heat exchanger 3, in the flow path, which in turn is in operative connection with the plate heat exchanger 10.

[0032] The phase change material, which is not shown in more detail, is in the form of small plate-shaped segments and is arranged in a container of the PCM storage system 12, which is also not shown in more detail. The water-glycol mixture of the secondary circuit flows around the phase change material in this container. The phase change material can largely be any material available on the market for this purpose, preferably paraffin waxes with a melting point of between 0° C. and 15° C. or water.

[0033] Furthermore, the PCM storage system 12 and the water heat exchanger 3 in the secondary circuit are each operatively connected to a separate three-way valve 14. The two three-way valves 14 can be switched in such a way that the PCM storage system 12 and the water heat exchanger 3 can be bypassed using an associated bypass line, this dependent on the current operating mode of the air-conditioning system.

[0034] An air-conditioning system set up in this way is operated in such a way that, during operation of a rail vehicle while traveling outside a tunnel, the chiller 1 primarily charges the cold storage unit/PCM storage system 12 with cold. At the same time, the cold storage unit 12 can thereby be charged with cold and cold can be provided for cooling the passenger compartment. In this operating state, the percentage ratio of the charging or provision of cold for the cold storage unit 12 and for the passenger compartment can be set. Alternatively, it is also possible that initially only the cold storage unit 12 is charged with cold and cold is provided for cooling the passenger compartment only once the cold storage unit 12 has been fully charged. If the chiller 1 is not being operated, which is to say, preferentially while driving in a tunnel, the cold energy stored in the PCM storage system 12 is fed to the water heat exchanger 3.