Master's Thesis Phillip Mehrfeld

 

Experimental Investigation of Air Handling Units in Laboratories

In this thesis a simulation model of an air handling unit is implemented into an existing building
model that is able to calculate the thermal energy consumption of buildings. Air handling units have
an energy demand that is not negligible. Therefore, thermodynamic equations are used to calculate
the energy demand for heating, cooling, humidification and dehumidification of an air mass flow.
The evaluation of the parametrisation of the air handling unit focuses on the required condition of
air in laboratories.
Additionally, experiments are realized by using a test rig, which includes a rotary heat exchanger to
recover heat between extract air and supply air, and is able to heat, cool and dehumidify the ambient
air.With a capacity to provide an air volume flow of about 4000m3/h the air handling unit of the test
rig is able to supply 160 m2 laboratory space with conditioned air. The relative deviations between
the simulated data and the measurement data are within the uncertainties for all experiments.
Furthermore, three laboratory buildings of a research centre are chosen to evaluate the effect of
the air handling unit as a part of the building simulation model. The discrepancies in total heat
demand between a simulation with activated and deactivated air handling module are 37 %, 58 %
and 90 % for these three buildings. In addition, a sensitivity analysis is performed to examine the
influence of different parameters. The greatest effect occurs by altering the permitted humidity and
leads to a difference of almost 60 % regarding the cooling consumption. Although there are certain
deviations in annual total heat demand between measurement and the results of the simulation
with reference parametrisation, it is possible to achieve a much better agreement by adjusting only
the parameters of the air conditioning model. The quality of this congruency is expressed by the
coefficient of determination. In a last step, the simulated heat output of the whole research centre
with 195 parts of buildings is compared to measurement data. The simulation results of the whole
research centre improve in terms of coefficient of determination.