Generic Superheat Control of Evaporators using One Sensor and One Actuator

Lyhne, Casper Hillerup ; Sørensen, Erik Baasch

10. term

Elektronik og IT, Kandidatuddannelsen (Spec. Intelligent Autonomous Systems)

2011

2011-05-31

137

Denne kandidatafhandling undersøger styring af overophedning (superheat) i et klimaanlæg ved kun at bruge én sensor og én aktuator. Overophedning er den ekstra opvarmning af kølemiddeldamp over dens kogepunkt; korrekt overophedning beskytter kompressoren. Systemet analyseres, og der afledes en udvidet model af fordamperen, som går ud over en konventionel model. Den udvidede model forbedrer forståelsen af overophedning, især når fordamperen er ujævnt fyldt. Der udvikles en modelbaseret overophedningsregulator, der udnytter kendskab til alle parametre; den bygges og testes på en testopstilling og viser positive resultater, hvilket demonstrerer, at styringsstrukturen er anvendelig. Regulatoren forenkles derefter til en generisk version, der kun måler fordamperens udgangstemperatur og ikke kræver forhåndskendskab til systemparametre. Den generiske regulator testes på to forskellige testsystemer og viser positive resultater på begge. Der indføres også feedforward (forudkobling) for at forbedre afvisning af forstyrrelser og den samlede ydeevne.

This thesis examines superheat control in an air-conditioning system using only one sensor and one actuator. Superheat is how much the refrigerant vapor is heated above its boiling point; maintaining it helps protect the compressor. The system is analyzed, and an extended evaporator model is derived that goes beyond a conventional model. This extended model improves understanding of superheat, especially when the evaporator is unevenly filled. A model-based superheat controller that uses full parameter knowledge is built and tested on a lab setup; it shows positive results and demonstrates the feasibility of the control structure. The controller is then simplified to a generic version that only measures the evaporator outlet temperature and does not require prior knowledge of system parameters. This generic controller is tested on two different test systems and shows positive results on both. Feedforward is also added to improve disturbance rejection and overall performance.

[This abstract was generated with the help of AI]

Refrigeration system ; Vapor compression ; Evaporator ; Superheat ; Control ; Estimation ; variance ; Air conditioning

Download
View record in AAU Student Projects