Master's Thesis Chen Yu


Analysis and optimization of the Life-Cycle-Costing of various hydraulic supply variants of HVAC systems

Chen Yu Copyright: EBC Methodology for the analysis and optimization of the LCC of HVAC systems with different supply

Due to the high demand-related costs of HVAC systems, a life-cycle cost assessment should also be carried out from an economic point of view in investment decisions. In this thesis, a methodology has been developed that simulative determined and assessed the LCC of a HVAC system with special consideration of the influence of hydraulic supply variants in Modelica.

For this purpose, a simulation model with required components of a HVAC system for various hydraulic supply variants was developed in combination with corresponding control strategies. This model can be used to determine the energy requirements for HVAC systems of buildings under different boundary conditions. The LCC of HVAC systems of various hydraulic supply variants were analyzed and assessed using the net present value method.

The throttling circuit with a speed-controlled pump and with a high temperature spread is the energetically and economically best variant for the applications in the thesis. In the case of mass-constant circuits, the mixing circuit is more energy efficient than the injection circuit and necessary for the air pre-heater in order to avoid freezing in winter. A higher temperature spread between the supply temperature and the return temperature not only allows the electrical energy requirements of the pumps to be minimized, but it can also enable higher efficiency of heat generators.