Valve influence on the power requirement of centralized pumps in hydronic heating systems - Theoretical study and evaluation of MathModelica as a hydronic systems simulation tool
Ladda ner
Typ
Examensarbete för masterexamen
Master Thesis
Master Thesis
Program
Publicerad
2009
Författare
Gruber, Mattias
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
This master thesis was performed in collaboration with the company Tour & Andersson AB (TA). The purpose was to evaluate if the systems modeling and simulation software MathModelica, can be used in the area of hydronic systems. The basis for the evaluation was a requirement specification, containing the following four requirements: 1. the software should find solutions to hydronic systems of relevant sizes, 2. the software should be able to be used to model both balancing and control valves as well as other common hydronic components 3. the software should be able to produce results which agrees to reality regarding systems behavior, and finally, 4. the software should be able to produce results which agrees to reality regarding numerical accuracy The evaluation was performed by executing two individual studies, which together were of such comprehensiveness that all four requirements were represented. One of these studies was called the verification study, and was used to test the fourth requirement presented above. The verification study was performed by model a test rig located at TA and to compare measured and simulated data. The result showed that the difference between the simulated and measured values normally was about ±7 %, which was considered as acceptable. However, much larger errors were also encountered in one case. For that reason, this requirement was not considered as fulfilled. The other study was called the reference study and was an evaluation of how ba-lancing and control valves in hydronic heating systems affect the power consumption of an including centralized pump. This study was used to test requirement one to three, and it was executed by modeling a general hydronic distribution system, as well as balancing and control valves. By simulating this system without any valves, only containing balancing valves and finally also with control valves, the effect that the gradual introduction of valves had on the drive power consumption of the pump was shown. Furthermore was the study broaden by including three different types of pumps as well as including both steady and unsteady conditions for which the power consumption was observed. The result showed that the power consumption of the pumps in all cases was decreased when valves were introduced. The primarily reason for this was that the flow level in the system was decreased enough to overcome any other negative effects. Hence, it was theoretically shown that the flowrate has the largest effect on the drive power consumption of a centralized pump. In conclusion, requirement three was considered as fulfilled, while requirements one and two were considered as fulfilled in most, cases but not in all, cases.
Beskrivning
Ämne/nyckelord
Byggnadsteknik , Building engineering