Teknillinen tiedekunta, 2012
Jukka Kiijärvi/Seppo Niemi
Sähkö- ja energiatekniikan koulutusohjelma (DI)
Builders and heat pump and pipe manufactures have faced new challenges as the demand on efficiency has become greater in the geoenergy sector. One method that can be used for increasing the heat transfer capacity in the heat collection systems is to use twisted tape or axially placed fins inside heat collection pipes. These inner structure modifications increase turbulent flow behavior which increases the heat transfer effect by force of convection.
The aim of this thesis was to model fluid flow behavior inside the heat collection pipes with the finite element method. The most important properties which need to be taken into account in order the heat collection fluid flow to be rather turbulent than laminar, are analyzed. The analysis consists of modeling with COMSOL Multiphysics. COMSOL Multiphysics is a finite element method - based on modeling and simulation software.
In this thesis flow behavior inside heat collection pipes with different inner surface structures was modeled. The aim was to find out what kind of flow environment would turn the flow from laminar to turbulent inside the heat collection pipes. Also how the pressure drop and pumping power vary when the inner profile of the heat collection pipe changes is examined. The models that have been built are meant to be mainly indicative. The aim of this thesis was not to design a completely new pipe profile. The aim of this thesis was to demonstrate how turbulent flow behavior in the heat collection pipes of a ground source heat pump system can be achieved. COMSOL models showed that a minor inner surface modification increases turbulence inside the heat collection pipes. The models and results discussed in this thesis are well known and very common in heat recovery engineering solutions, but they have not been discussed before in the field of ground source heat pump systems and heat collection pipes.
heat collection pipe, fluid flow, heat transfer by convection, computational fluid dynamics, finite element method