After a lot of preparative work by the consortium, finally the construction of the thermoacoustic part of the TAP was completed by last week. The high- and low temperature heat exchangers and regenerators are assembled to single units, provided with thermocouples, mounted in the pressure vessel and connected to the high and low temperature fluid circuits. Also the data-acquisition system was installed for real time measuring temperatures and acoustic power. The complete test setup of the TAP is depicted below.
At the construction location no 100 kW (waste) heat is available therefore a controllable heat source (9 kW electric oil heater) is used simulating the flue gas heat exchanger. This temporarily heat source allows for measuring static heat loss, onset temperature and the increase of acoustic loop power with temperature difference in the low power range.
Based on well known scaling rules the power levels in the TAP will be one order of magnitude less but the system will be thermoacoustically similar to the final system (using helium at 600 kPa) when filled with air at 240 kPa. This “similitude” allows for judging the performance of the TAP and for validating the simulations.
As a first result, the onset temperature difference of the TAP was measured to be 29 K between the high temperature (49°C) thermal oil and the low temperature (20°C) water circuit which agrees well with the simulated values.
This is an encouraging result because a low onset temperature is a key parameter and absolute requisite for successful operation of waste heat recovery systems. So the first test is passed and more test will follow.