Increasing COP of automobile AC system by using Energy Harvesting Suspension

Usually only 10-16% of the fuel energy is used to drive the vehicle to overcome the air resistance and air drag. Regenerative shock absorbers have the ability to continuously recover a vehicle's vibration energy that is otherwise dissipated due to road irregularities, vehicles acceleration and braking, further using this energy for better suspension control. Energy harvesting shock absorber can be used as source of energy regenerative system. It can be installed in the vehicle with less modification in the conventional suspension system.

Our concept consists of:
1) Shock absorber (which is used as a compressor)
2) Ranque-hilsch tube (vortex tube)
3) Ducts
4) AC system of an automobile

In this shock absorber a piston cylinder arrangement is used due to which it acts as a compressor. It has two valves:
1) Non-return suction valve
2) Non-return delivery valve

Air is sucked in through a filter mounted at the inlet of suction valve. And the compressed air leaves through a delivery valve which opens only when a certain pressure is reached. During compression air exerts a retarding force on the piston hence producing a damping effect. The compressed air is passed to the inlet of the vortex tube via a long duct (long for proper heat dissipation).

Compressed air enters the tube tangentially through a nozzle forming a vortex kind of motion. The diaphragm prevents the leftward motion of the vortex , therefore, it travels to the right hand side of the tube called hot air. The throttle valve opening controls the temp and proportional of the cold stream with respect to hot stream. The heat transfer takes place between the slower moving air and faster moving incoming air. The cooled air flows through the center of the generator and exits through the cold air exhaust port. We decided to use vortex tube since it uses air as a refrigerant and has no leakage problem. Also it is light in weight and requires less space.
The cold air from vortex tube is used to sub-cool the refrigerant from the condenser outlet of automobile AC system. This reduces the temperature of the refrigerant from the condenser, hence the refrigeration effect increases. And thus coefficient of a performance (COP) of the AC system also increases.

The shock energy in suspension system is used to increase the COP of AC system and hence reduce the work of compression of AC system to increase refrigeration effect.

Serial no Name
1 Suction valve with filter
2 Piston
3 Delivery valve
4 Delivery pipe
5 Vortex tube
6 Liquid sub cooler
7 condenser


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  • Name:
    Shraddha Barawkar
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    Team members:
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