Master's Thesis Steffen Wiegmann

 

Integration of dynamic boundary conditions in the design process of heat pump systems

The efficiency of a heat pump system depends on dynamic boundary conditions, which include
the weather and user behaviour. Hence, for designing and operating a heat pump system the
dynamic boundary conditions must be observed.
Therefore, in this work a detailed simulation model of a single-family dwelling is developed. In
this model the outside temperatures, solar radiation and wind speeds from weather data as well
as the internal loads and the ventilation behaviour of the user are integrated. This model contains
an air-to-water heat pump, a heating element, a domestic hot water tank and a hot water tank. Investigations
are made at the locations Aachen, Freiburg, Frankfurt an der Oder and Bremerhaven.
For the Evaluation the SCOP is used.
With the simulation model a new regulation for the determination of the temperature of the heating
water storage tank is developed. Thereby, the maximum required flow temperature of the
radiators are determined for keeping the room temperature at the setpoint. Thus, the storage tank
temperature is reduced by 1,26ąC and the SCOP of the heat pump is increased by 1,85 %.
Furthermore, the heat transfer network is investigated. For that, the influence on the utilization
of the radiator is determinated. Subsequently, an improvement of the SCOP of 12,45% is achieved
by changing the heat transfer network.
At the end, a reduction of the room temperature set point is investigated with a rule base control
during absence of the user. This reduces the energy consumption by 16,4 %.
In further work, different parameters must be investigated. The size of the storage tank, the heating
rod and the heat pumpmuss be varied. The user behaviourmust be varied, aswell. In addition
to the energetic consideration, a financial analysis and an evaluation of the user comfort must be
observed.