Robert Santa

Robert Santa
Visoka tehnička škola strukovnih studija | VTS · renewable energy sources

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10
Publications
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68
Citations

Publications

Publications (10)
Article
Full-text available
The aim of this study was to develop a mathematical model with lumped parameters to investigate the energetic parameters of the heat pump with an internal heat exchanger (IHX). The developed mathematical model is validated with 25 tests using R134a as a working fluid. The results show that the maximum prediction error between the modeled and experi...
Article
Full-text available
The presence of the lubricant POE 68 in the refrigeration system changes the thermophysical properties of the refrigerant, which significantly affects the heat transfer and the hydraulic processes. The purpose of this research is to investigate the thermodynamic properties of the R152a, R125, R134a and R123 refrigerant and POE 68 lubricant mixtures...
Article
Full-text available
This research presents an energy performance analysis of the heat pump system with internal heat exchanger (IHX). The mathematical model of the heat pump outlined in this paper has been created by the author, it is steady-state with lumped parameters. The experimental validation of the model has been carried out using R1234yf and R134a as refrigera...
Article
Full-text available
Coordinate measuring machines are devised for most complex measurements. Besides their dimension measuring abilities, the CNC operated machines can measure geometrical characteristics of form, such as straightness, roundness, cylindricity, etc. These are vital features currently, when inspection needs to submit very thorough reports not only on the...
Article
The purpose of the presented research is to develop an overall mathematical model, which will allow for a more precise simulation of the operation of a water-to-water heat pump system, having in mind its thermodynamics, fluid mechanics and heat transfer processes. The simulation allows the prediction of the parameters of the state at each and every...
Article
The purpose of this study is to produce a mathematical model to describe the operation of a water-to-water heat pump system for steady-state condition. The set-up model is deterministic. It consists of distributed as well as lumped parameters. The proposed mathematical models of heat exchangers were described by coupled differential equations, whil...
Article
Full-text available
In our earlier studies, it has been stated that the validity and limits of correlations developed for the calculation of heat transfer processes in the evaporator and condenser of heat pumps are not published in general. The values yielded for model structures and process characteristics indicate extreme ranges of standard deviation. While the desc...
Article
The article aims to present, analyze and select two-phase condensation heat transfer coefficients for the refrigerant-side in the condenser of the heating and cooling system of a heat pump. The heat transfer models are analyzed for condensation in horizontal smooth tubes. The mathematical models published by various authors refer to the range of he...
Article
Full-text available
This paper presents the analysis of the structure of a heat pump heating system. The water-water heat pump components of energy input to output and economic factors in decision-making are described in this work.
Article
The author introduces and analyses the two-phase pressure drop correlation for refrigerant R134a in the condenser of a heat pump heating-cooling system. The following correlation will be included: the Lockhart and Martinelli, Friedel, Chrishom, Tran et al, Wang et al. and the Wilson et al. The previously mentioned correlations were analyzed numeric...

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