Sustainable air conditioning one step closer

Sorption cooling technology developed by ECN delivers enough cooling for comfortable interior temperatures in cars. This is the preliminary conclusion based on the ongoing TOPMACS project. A good foundation has been established to develop a prototype for passenger cars. This brings the ?sustainable? air conditioner ? that does not require additional power but only uses residual heat from the car ? to the next development stage.

It is common knowledge that conventional air conditioning systems are detrimental to the environment. These car air conditioners require extra engine power. This results in an increased fuel usage and higher CO2 exhaust levels. Leakage of polluting cooling agents (H(C)FCs) is a big contributor to the greenhouse effect. Add to that the fact that European regulations will restrict the use of H(C)FC cooling agents in future compact air conditioning systems, and it is clear that an alternative technology must be made available. ECN is developing a new technology that will solve the cooling agent problem, and reduce added fuel use dramatically.

Sorption Cooling

Sorption cooling is a technology that uses heat to generate cold. The principle is based on reversible sorption reactions between a vapour and a solid. In this case, the system uses silica gel for its solid, and water vapour. Cooling is the result of the evaporation of water. Water vapour is absorbed by powerful water-attracting silica gel. (Residual) heat from the engine is required to regenerate the silica gel, so that water vapour is again released from the gel.

Four prototypes were built on laboratory scale by project partners in the first phase of the project. Three of these have been extensively tested. Based on test results, the ECN sorption cooling system has been selected for the next phase in the project: building and testing a prototype in a passenger car. Because Fiat is an important research partner, it will be a Fiat Grande Punto. The cooling system by project partner CNR-ITAE is being tested in an Iveco Stralis, a truck also originating from Italy.

?This is actually a breakthrough,? ECN researcher Robert de Boer told us. ?We have proved that our innovative and energy-saving sorption technology will provide enough cooling for comfortable interior temperatures in a passenger car. End users like Fiat and Iveco have so much faith in the concept that we can now take the concept another step forward. We will adapt our cooling system so that it can be built into the boot of a test car and then performance can be tested under actual operating conditions. However, we will need to adjust the design of the evaporator and the condenser and rebuild these components before that time.?

Because it is a prerequisite that new cooling technology must be able to provide at least the same level of comfort as conventional technology, a parking heater will probably be used. De Boer: ?This heater will provide heat for the cooling system just in case not enough residual heat from the engine is available, such as after a cold start. In addition, it provides the option of disconnecting the cooling system from the engine, so that the air conditioner can also provide cool air when the motor is not running.?

Robert de Boer
ECN Energy Efficiency in Industry
Tel. (+31) 224 - 564871