Thermal comfort

Thermal comfort modelling

Project partnet: Airbus S.A.S.

The assessment and prediction of the local comfort in air flows is becoming more and more complex by means of new ventilation concepts and the use of comfort models. In the framework of previous projects, the 33 knot comfort model (33NCM) was developed at the Chair for Building and Indoor Climatics, which is expanded in its scope of application. The model parameterisation is based on test subjects under different thermal conditions. The exact detection and reproducibility of the boundary conditions is often difficult. In order to extend the scope of the model, test experiments were carried out in a highly modular comfort cube, the Aachen Comfort Cube (ACCu).

The Aachen Comfort Cube

Copyright: EBC

The evaluation and prediction of local thermal comfort is becoming increasingly important. In order to predict the thermal comfort in environments with different vertical temperature gradients, a 33 node comfort model (33NCM), which can estimate the local and global thermal comfort was developed previously. The body of the human is divided into 16 segments and every segment has a skin and a core layer. These different body parts are connected with a central virtual blood node. All major heat transport processes between the nodes are simulated and balanced. In order to improve the models accuracy, a highly modular test chamber, the Aachen Comfort Cube (ACCu), was built in order to evaluate the thermal comfort in indoor environments by test subjects. The thermal environment in the cube can be mapped to different situations with variable surface temperatures and a variable air distribution system.

The comfort cube has a floor area of 2 m x 2 m and a height of 2.5 m. Three of the surrounding side walls are divided into four surface segments. The first and the third segment are 400 mm high, the second is 500 mm and the fourth segment is 1050 mm high. A test subject can stand and sit in the comfort cube.

Copyright: EBC

Each surface segment can be set to a temperature between 15 C and 40 C, including the ceiling and the ground segments. In every surface segment capillary tube mats are installed. Warm or cold water can flow through the capillary tube mats and heat up or cool down each surface segment separately. The warm water for the surface segments is heated up by instantaneous water heaters.

Different ventilation concepts can be investigated by using a variable air distribution system, mixed ventilation concepts are reached with a swirl diffuser or slot diffusers at the ceiling. Displacement ventilation is implemented by vertical ventilation slots above the floor. The supply temperature can be set between 15 C to 40 C.