Razvoj uređaja za ocjenu termodinamičke valjanosti sa zeotropskim smjesama

Soldo, Vladimir (2000) Razvoj uređaja za ocjenu termodinamičke valjanosti sa zeotropskim smjesama. = Development of device for estimation thermodynamic efficiency of process with zeotropic mixtures. Scientific master's thesis , Sveučilište u Zagrebu, Fakultet strojarstva i brodogradnje, UNSPECIFIED. Mentor: Ćurko, Tonko.

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Abstract (Croatian)

U radu je razvijena mjerna linija s rashladnim uređajem koji omogućuje rad po načelu Lorenzovog procesa (primjena zeotropske smjese) i Carnotovog procesa (primjena azeotropske smjese, odnosno jednokomponentne radne tvari). Osnovni elementi uređaja su poluhermeticki štapni kompresor, protustrujni cijev-u-cijevi isparivač i kondenzator, te termoekspanzijski ventil. Uredaj je opremljen instrumentima i osjetnicima za mjerenje svih relevantnih veličina (temperature, tlaka i protoka), te je spojen na sustav za njihovo pohranjivanje i obradu. U radu se provodi analiza termodinamičke valjanosti ljevokretnog rashladno-ogrjevnog procesa u radu sa zeotropskom smjesom R407C i uspoređuje s procesom u radu s jednokomponentnom radnom tvari R22. Eksperiment na rashladnom uređaju sastoji se od mjerenja temperatura na ulazima i izlazima iz izmjenjivača, kako na strani radne tvari tako i na strani hladenog medija, odnosno, rashladne vode, mjerenja protoka u primarnom krugu i u oba sekundarna kruga, mjerenja tlaka isparivanja i tlaka kondenzacije, mjerenja pada tlaka na izmjenjivacima i mjerenja elektricne snage elektromotora kompresora. Mjerene vrijednosti temperature, tlaka i protoka obraduju se priredenim LabVIEW programom koji koristi izvorne datoteke REFPROP programa za izračunavanje termodinamičkih i fizikalnih svojstava radnih tvari, te daje rezultate za učin isparivača i kondenzatora za obje korištene radne tvari. Dobiveni rezultati pokazuju da će ekološka radna tvar R407C , koja je prema današnjim standardima prihvatljiva obzirom na zaštitu okoliša, biti dobra zamjena za jednokomponentnu radnu tvar R22 pri visim temperaturama isparivanja. Iako su teorijski rezultati ukazivali da će, energetski gledano, R407C biti bolja radna tvar nego R22 rezultati su to opovrgli. Razlozi leže u slabijem prijelazu topline u procesu s radnom tvari R407C.

Abstract

The paper describes the experimental rig with a refrigerating system which enables operation according to Lorenz (zeotropic mixture application) and Carnot process (application of azeotropic mixture and pure refrigerant). The basic system elements are semi-hermetic reciprocating compressor, countercurrent tube-in-tube evaporator and condenser and thermoexpansion valve. The system is equipped with instruments and sensors for measuring all relevant data (temperature, pressure and flow rate), and is connected to the system for their acquisition and analysis. The paper also refers to thermodynamic efficiency of left-handed refrigerating-heating process operating with a zeotropic mixture R407C and it is compared to the process operating with pure refrigerant R22. The experiment on refrigerating system consists of measuring temperature at exchanger inlets and outlets on both refrigerant sides and on coolant and cooling water, measuring flow in primary loop and in both secondary loops, measuring evaporation and condensation pressure, measuring pressure drop on exchangers and measuring electric power of compressor's motor. The measured temperature, pressure and flow values are processed by means of LabVIEW programme which uses source program REFPROP databank for refrigerant thermodynamic and physical properties calculation and yields results of cooling capacity and heat capacity of both refrigerants. The obtained results show that environmentally friendly refrigerant R407C will make a good substitute for transitional refrigerant R22 at higher evaporation temperatures. Although theoretical results have lead to an assumption that R407C will energetically make a better refrigerant than R22, the experimental results have shown differently. It is because, in the heat exchange process with R407C refrigerant there is lower heat transfer coefficient.

Item Type: Thesis (Scientific master's thesis)
Uncontrolled Keywords: mjerna linija; rashladni uređaj; zeotropske smjese; Lorenzov proces; termodinamička valjanost procesa
Keywords (Croatian): experimental rig; refrigerating system; zeotropic mixtures; Lorenz process; thermodynamic efficiency
Divisions: 300 Department of Thermodynamics, Thermal and Process Engineering > 320 Chair of Thermal and Process Engineering
Date Deposited: 22 Sep 2014 18:00
Last Modified: 16 Oct 2015 13:19
URI: http://repozitorij.fsb.hr/id/eprint/152

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