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New doctoral dissertation

June 11, 2025

VILNIUS TECH Library invites you to follow the published new dissertations. The dissertation „Investigation of operating modes of a variable circuit volume heat pump in a mechanical ventilation system“  („Kintamo kontūro tūrio šilumos siurblio veikimo režimų tyrimas mechaninio vėdinimo sistemoje“) prepared by VILNIUS TECH, Anton Frik. The dissertation was prepared in 2019–2025. Scientific Consultant – Prof. Dr Habil. Vytautas Martinaitis.

The dissertation was defended at the public meeting of the Dissertation Defence Council of the Scientific Field of Mechanical Engineering in the Aula Doctoralis Meeting Hall of Vilnius Gediminas Technical University at 10 a.m. on 11 June 2025.

The dissertation investigates the thermodynamic operating cycle and parameter control of a heat pump integrated into a mechanical ventilation system through analytical, experimental research, and numerical modelling. The research explores how variations in the heat pump circuit volume influence system efficiency under changing outdoor air conditions. The primary aim is to develop a control method to enhance the seasonal operating efficiency of a heat pump integrated into a building ventilation system. The dissertation addresses several key objectives: developing an analytical thermodynamic model and performing parametric analysis; designing and constructing an experimental test bench, followed by experimental investigations under various operating conditions; creating a mechanism for adjusting the heat pump circuit volume and evaluating its impact on system parameters and seasonal efficiency. The dissertation consists of an introduction, three chapters, general conclusions, references, the author’s publications on the topic, and two appendices. The introduction discusses the research problem and relevance, describes the object of investigation, formulates the aim and specific objectives, outlines the methodology, highlights the scientific novelty and practical significance, and presents defendable statements. It concludes with an overview of the author’s publications and conference presentations related to the topic, and a description of the dissertation structure. The First Chapter provides a literature review on heat pump applications in ventilation systems, their control principles, and technological solutions. It identifies key research directions and refines objectives. The Second Chapter describes the research methodology, the design of the experimental setup, and the procedure for conducting the tests. Additionally, the chapter outlines the operating algorithm of the numerical heat pump model and seasonal efficiency evaluation principles. The Third Chapter presents the results of analytical, experimental, and numerical modelling studies. It evaluates the impact of circuit volume adjustment on the performance and efficiency of the heat pump under varying operating conditions and provides a comparative analysis of heat pump operation in European regions with different climates. Nine scientific publications related to the dissertation have been published, including two in peer-reviewed journals indexed in Web of Science with citation indices. The results have been presented at four international scientific conferences in Lithuania and abroad.

Doctoral dissertation readers can search via VILNIUS TECH Virtual Library.

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New doctoral dissertation
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