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Copyright of Science: Future of Lithuania / Mokslas: Lietuvos Ateitis is the property of Vilnius Gediminas Technical University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Science: Future of Lithuania / Mokslas: Lietuvos Ateitis is the property of Vilnius Gediminas Technical University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper analyzes an experimental heat pump used for heat recovery in a mechanical room ventilation system. The aim of the work is to examine the operation, control logic of the heat pump and evaluate the possibilities of its operation modes, cycle control by outdoor air temperature. A review of scientific literature and experimental tests of the heat pump were performed to achieve this goal. Tests were performed in three stages, after each stage, according to the results obtained the heat pump stand was improved and experimental modes were adjusted. During the experiment, the tendencies of the heat pump freon and air involved in the heat exchange parameters are analyzed with different combinations of expansion valve positions and compressor power. Knowing these experimental characteristics, the extent to which the combination of these two controls can be used to efficiently control of the heat pump according to the outside air temperature is assessed. Based on the results of the research the heat pump control algorithms (depending on the variable outdoor air temperature) are prepared. Santrauka Straipsnyje analizuojamas eksperimentinis šilumos siurblys „oras–oras“, kuris naudojamas šilumai atgauti mechaninėje patalpos vėdinimo sistemoje. Darbo tikslas – ištirti eksperimentinio šilumos siurblio „oras–oras“ veikimą ir pasiūlyti jo veikimo ciklo valdymo algoritmą didesniam sezoniniam efektyvumui gauti. Tikslui pasiekti buvo vykdomi šio įrenginio eksperimentiniai bandymai. Jie atlikti trimis etapais. Po kiekvieno etapo, atsižvelgiant į gautus rezultatus, buvo tobulinamas šilumos siurblio stendas, tikslinami jo valdymo režimai. Eksperimento metu analizuojamos šilumos siurblio freono ir šilumos mainuose su juo dalyvaujančio oro parametrų kitimo tendencijos, esant skirtingiems droselinio vožtuvo atidarymo pozicijos padėties ir kompresoriaus galios deriniams. Žinant tokias eksperimentines charakteristikas, įvertinama, kiek šių dviejų valdymo priemonių derinys gali būti naudojamas efektyviam šilumos siurblio valdymui pagal išorės oro temperatūrą. Remiantis atliktų tyrimų rezultatais pasiūlyti šilumos siurblio valdymo, priklausančio nuo kintančios lauko oro temperatūros, algoritmai. Reikšminiai žodžiai: ciklas, freonas, šilumos siurblys „oras–oras“, šilumogrąža, valdymo algoritmas, vėdinimo sistema.

This paper evaluates the seasonal thermodynamic efficiency of the air-to-air heat pump used for a heat recovery ventilation system and several modulations of compressors affecting the thermodynamic efficiency of the heat pump. A variable speed and on/off-type compressors have been selected. In order to evaluate the thermodynamic potential of the device, energy analysis has been performed. Along with modelling the operation of the air handling unit during the cold time of the year, variations in the thermodynamic efficiency or different modulation compressors have been compared. The obtained results have shown that the use of a few simple compressors causes a decrease in the seasonal parameters of the heat pump: heat generated by a condenser is 5% lower compared to the use of variable speed compressors and therefore the seasonal coefficient of the performance (COP) of the heat pump decreases by 5%. Possible improvement on the heat pump can be provided changing the compressor into variable speed or modulatory equipment, which allows adjusting to heat demand and thus increases the seasonal efficiency of the system from a thermodynamic point of view.Article in Lithuanian