You are correct that the compressed air will heat up and any losses through the tank walls will reduce the efficiency of the engine. The simplest solution is to insulate the tank. Several designs are currently being considered and they involve external insulation as well as the materials used to construct the tank. By utilizing the appropriate design, heat loss through the tank walls should not be a significant effect on the overall efficiency of a vehicle.

We are familiar with the UCLA study. In that study, a conventional engine was fitted with electrically actuated variably controlled valves. The valves are used to switch the operating modes of the engine between engine (or firing) mode, air compressor mode, and air motor mode. The firing mode is the normal operation of the engine using combustion to power the vehicle. In the compressor mode, the variable valves are actuated to make the engine operate like an air compressor - storing compressed air in a storage tank. In the air motoring mode, the valves are actuated so that the compressed air in the tank can be used to push on the pistons and move the vehicle without the assistance of combustion. The system works; however, the valve-control and mode switching is very complicated. In addition, because all cylinders need to handle combustion as well as compression, their ability to compress air and pump it into an external tank is limited by the clearance volumes that are required for the combustion process.

In the Scuderi Engine, the split-cycle arrangement separates the functions of compression and combustion. Compressed air is produced during the normal operation of the engine and is then used in the normal combustion process of the engine. This is ideal for an air-hybrid application because the normal operation of the engine does not need to change. In addition, since the compression cylinder is separated from the combustion process, its clearance volumes and compression ratios are better suited for pumping high pressure air into an external tank.

Best regards,
Sal Scuderi, President
The Scuderi Group

The nice part about pneumatic systems is they have been around for decades and are very well developed in terms of both performance and safety. For example, today’s air tanks, if punctured, are designed to tear not to rupture. So even if there is a major puncture in the tank, what happens is a release of the air which will create a loud noise but will not cause injury.

Over pressurizing the tank is controlled by pressure relief valves. The pressures in the tank will be approximately 50 bar or 735 psi, and the tank size will be about 10 liters for each cylinder pair.

Also the tank does not have to be located under the hood it can be located anywhere in the vehicle. It most likely will be placed somewhere under the vehicle.

Thanks for your question.

Regards,
Sal Scuderi
President, The Scuderi Group

Also, I assume you are aware of the work Ford was doing with Prof. Tsao at UCLA on air hybrids. How does your design compare to theirs?