Charge distribution in a 5 kW heat pump using propane as working fluid: Part II: Modelling of liquid hold-up
2001 (English)In: 16 Nordiske Kølemøde og 9 Nordiske Varmepumpedage: København, 29.-31. august 2001 : proceedings, Autoriserede Kølefirmaers Brancheforening , 2001Conference paper (Other academic)
A theoretical model for prediction of the amount of refrigerant in condenser and evaporator of a 5kW capacity heat pump is developed. Condenser and evaporator of the experimental test rig are SWEP Brazed Plate Heat Exchangers (BPHE). Plate heat exchangers are widely used in refrigeration and heat pump applications today. However, the mechanisms of boiling and condensation in BPHE represent a difficult issue, for which only few models are developed and presented in published literature.
The model presented in this article is developed using the Engineering Equation Solver (EES) software program (Alvarado, Klein). Input values for the calculations are the inlet/outlet temperature, mass flow rate and pressure readings taken on the test facility.
For modelling, evaporator is conventionally divided in two parts: boiling part and superheating part, for which heat transfer calculations are performed in order to find the respective heat transfer areas. For the boiling part of evaporator, void fraction is predicted and mass of liquid and vapour in the whole evaporator is calculated.
Condenser is divided in desuperheating, condensing and subcooling parts and heat transfer calculations are performed in order to define heat transfer areas for each of them. In the condensing part, a film thickness based on the Nusselt theory is assumed and, afterwards, total mass of liquid and vapour in the whole condenser is calculated.
The obtained results are compared to the measured amount of refrigerant in evaporator and condenser and interpreted.
Place, publisher, year, edition, pages
Autoriserede Kølefirmaers Brancheforening , 2001.
heat pump, charge, propane, modelling
IdentifiersURN: urn:nbn:se:kth:diva-76368OAI: oai:DiVA.org:kth-76368DiVA: diva2:491011
16 Nordiske Kølemøde og 9 Nordiske Varmepumpedage, Köpenhamn, 2001
QC 201202282012-02-282012-02-062014-09-22Bibliographically approved