Modeliranje apsorpcijskog rashladnog procesa pokretanog solarnom energijom

master's thesis

• Title (english): The modelling of a real absorption cooling process powered by solar energy
• Author: Andreja Žužić
• Mentor: Veljko Filipan (mentor)
• Committee member: Veljko Filipan (predsjednik povjerenstva)
• Committee member: Igor Sutlović (član povjerenstva)
• Committee member: Željka Ujević Andrijić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2017-06-27, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Chemical Engineering; Analysis, Synthesis and Management of Chemical Processes

Abstract

Cilj rada bio je projektirati, dimenzionirati i matematički modelirati konkretan apsorpcijski rashladni uređaj koji kao radni medij koristi binarnu smjesu LiBr/voda. Proučavani uređaj instaliran je u sklopu solarnog rashladnog postrojenja u Dubrovniku namijenjenog hlađenju poslovne zgrade tvrtke Vodovod Dubrovnik. Potrebnu energiju za pokretanje apsorpcijskog rashladnog procesa uređaj dobiva putem polja solarnih kolektora površine 60 m^2, a za ublažavanje oscilacija Sunčevog zračenja i/ili oscilacija rashladne energije, u sustav su također ugrađeni spremnici vrele i hladne vode volumena 3 i 1 m^3. Za projektiranje i dimenzioniranje uređaja razvijen je matematički model u softverskom paketu ChemCAD te je validiran na nezavisnom skupu eksperimentalnih podataka iz literature. Model je nakon validacije korišten za određivanje površina izmjene topline te ukupnih koeficijenta prijelaza topline pojedinih procesnih jedinica unutar uređaja. Tako dobiveni podaci korišteni su zatim za razvoj matematičkog modela u softverskom paketu MATLAB koji je nakon validacije primijenjen za određivanje optimalnih radnih uvjeta uređaja pri kojima postiže nominalni rashladni učin od 17,5 kW. Na temelju razvijenih matematičkih modela provedene su analize osjetljivosti kojima je utvrđeno da na ostvareni rashladni učin i stupanj iskorištenja procesa najveći utjecaj imaju ulazne temperature vanjskih ogrjevnih i hladnih struja. Analizom je također utvrđeno da povišenje temperature na izlazu iz kondenzatora i apsorbera dovodi do smanjenja rashladnog učina i stupnja iskorištenja procesa, dok im povišenje temperature na izlazu iz isparivača pogoduje. Osim toga, efikasnost rada uređaja bit će veća što je viša izlazna temperatura jake otopine LiBr na izlazu iz generatora te što je veća efikasnost izmjenjivača topline.

Abstract (english)

The aim of this paper was designing, dimensioning and mathematical modelling of a real absorption cooling device which uses binary mixture LiBr/water as working media. The studied device is installed as a part of the solar cooling plant in Dubrovnik in order to provide cooling for an office building of Vodovod Dubrovnik company. The energy needed for starting the absorption cooling process is provided through the solar field with total absorption area of 60 m^2. Besides that, 3 m^3 hot water tank and 1 m^3 chilled water tank are also embedded into the plant to reduct oscillations of Solar radiation and/or cooling capacity. In order to design and determine the dimensions of the device, a mathematical model was developed in ChemCAD software package and validated using an independent set of experimentally data from literature. After the validation, the model was used for the calculation of heat transfer area and coefficients of every process unit inside the device. This calculated data was then used during the MATLAB mathematical model development which was also validated and then used for determination of optimal working conditions of the device in order to achieve nominal cooling capacity of 17.5 kW. Sensitivity study was also done using the developed mathematical models. The results have shown that inlet temperatures of hot and cold utility streams have the main effect on the obtained cooling capacity and coefficient of performance of the system. Furthermore, it has also been found that temperature rise at the condenser and absorber outlet has negative effect on cooling capacity and coefficient of performance, while temperature rise at the evaporator outlet improves them. Besides that, higher temperature at the generator outlet and higher heat exchanger efficiency will also contribute to more efficient device operation.

• Keywords: solarno rashladno postrojenje; apsorpcija; LiBr; matematički model
• Keywords (english): solar cooling plant; absorption; LiBr; mathematical model
• Language: croatian
• URN:NBN: urn:nbn:hr:149:077178
• Study programme: Title: Chemical Engineering - Graduate study; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka kemijskog inženjerstva (magistar/magistra inženjer/inženjerka kemijskog inženjerstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2019-09-27 11:14:16