ENERGY ANALYSIS OF "SAFE HOUSE" BUILDING AND ENERGY IMPROVEMENT BY HEAT PUMP IMPLEMENTATION

Last few decades energy consumption in buildings increases. With a higher population and bigger requirements for comfort, energy needs grow exponentially. Concerning dispensation of the reserves of many energy fuels and energy ineffective work of HVAC systems, their optimization must be done. In such optimization, particular care should be taken not to damage thermal comfort. In order to promote the improvement of energy efficiency in buildings, for example, the Safe House building in Belgrade was taken. A system of hot-water heating with radiators and a heat pump as an efficient source of heat is designed. Afterward, the energy performances of the building were determined and an analysis of the energy consumption and CO2 emissions was carried out for the implemented system

THE EFFECT OF INTERNAL HEAT EXCHANGER IN A REVERSIBLE CO2 SYSTEM UNDER VARIOUS OPERATING CONDITIONS

The use of an internal heat exchanger (IHX) as a cycle improvement measure is very common with CO2 systems. However, a simple thermodynamic analysis is not able to fully indicate the advantages of IHX in a single-stage system. For this reason, in this paper, the effect of the internal heat exchanger on the reversible CO2 system, which can work in both air-conditioning and heating mode, was experimentally investigated. Experiments were performed under various conditions for both operating modes, with and without an internal heat exchanger. The results of the experiments showed that in the heating mode (heat pump) the coefficient of performance (COP) can be increased up to 10,5% by introducing the internal heat exchanger, while in the air-conditioning mode, the COP can be increased up to 13,8%. Also, it has been shown that this improvement provides safer system operation and less frost formation on the evaporator

ENERGY ANALYSIS OF "SAFE HOUSE" BUILDING AND ENERGY IMPROVEMENT BY HEAT PUMP IMPLEMENTATION

Last few decades energy consumption in buildings increases. With a higher population and bigger requirements for comfort, energy needs grow exponentially. Concerning dispensation of the reserves of many energy fuels and energy ineffective work of HVAC systems, their optimization must be done. In such optimization, particular care should be taken not to damage thermal comfort. In order to promote the improvement of energy efficiency in buildings, for example, the Safe House building in Belgrade was taken. A system of hot-water heating with radiators and a heat pump as an efficient source of heat is designed. Afterward, the energy performances of the building were determined and an analysis of the energy consumption and CO2 emissions was carried out for the implemented system

APPLICATION OF FINITE ELEMENT METHOD FOR ANALYSIS THE PARAMETERS OF FRACTURE MECHANICS

When making mechanical components, geometric imperfections are common, which in certain cases can cause a weak spot or some form of crack. Depending on the intensity and position of the action of forces on the mechanical component, its bearing capacity or load that the structure can carry with a given degree of safety directly results. The paper will compare the critical values of the stress intensity factor, as a basic element of fracture mechanics, obtained by empirical formulas and the values obtained by applying the finite element method. Using Abaqus, the values were verified numerically and the results of the analysis can be considered validated. The results showed deviations in the acceptable range and the application of the finite element method to the analysis of cracks in the material confirmed that Abaqus can also be used as an excellent tool in the analysis of fracture mechanics

VIRTUAL MODEL GENERATION OF REPRESENTATIVE VOLUME ELEMENT FOR UNIDIRECTIONAL COMPOSITE

Composite materials are widely used in different industries because of their unique characteristics that can be adapted depending on the application. Prediction of mechanical properties before the production process enables time-saving and optimization of geometry and materials. The purpose of this paper is to show the steps in virtual modeling of the elementary unit of the unidirectional composite. The first step is the computer generation of the virtual domain that needs to geometrically match the experimental sample. After that, the mesh of finite elements must be defined, and apply algorithms for periodic border conditions. The next step is setting the boundary conditions and forces. After obtaining contour plots (homogenization method) mechanical characteristics and effective elastic constants of the composite can be predicted. Thanks to the implementation of the finite element method in the ABAQUS program, it is possible to predict the mechanical characteristics of the composite depending on the variation of different parameters of the composite

OPTIMAL CHARACTERISTICS OF A SELF-EXPANDING NITINOL STENT UNDER THE ACTION OF ARTERIAL FORCES

Nitinol is a material widely known because of its super-elasticity characteristic which is important in the cyclic load area. Atherosclerosis is a disease of the modern age that involves blood vessels narrowing. If this condition is not properly treated, the consequences can be serious. Therefore, it is of great importance to study the optimal characteristics of the stent and the hemodynamic condition in the blood vessels. Self-expanding nitinol stents have been often used to treat arterial narrowing. This paper will analyze the influence of the ratio between the stent diameter and the blood vessel diameter and their correlation with radial forces in the case of atherosclerotic plaque or fibrous cap. Also, this paper will analyze recommended stent thickness to ensure satisfactory deformations at the end of the fatigue cycle

EFFECTS OF PURGING NON-CONDENSABLE GASES FROM AMMONIA REFRIGERATION SYSTEM

This paper analyzes the operational characteristics of the Tuzla brewery refrigeration system after the installation of the Danfoss IPS8 air purging device. In order for an analysis such as this to be conducted correctly, one must understand where in the brewing industry the need for refrigeration occurs, how non-condensable gases are accumulated inside of the refrigeration system, and how the separation of non-condensable gases is done. After the theoretical part of the analysis, in which the thermodynamic basics of the ammonia refrigeration cycle is explained, an analysis of annual savings was conducted. The results of the analysis are presented in the form of annual savings in electricity consumption, for different operating conditions of the specific refrigeration system with and without a purger. At the end of this analysis, the amount of released non-condensable gases were also calculated

COMPARATIVE ANALYSIS OF ELECTRIC ENERGY CONSUMPTION OF CASCADE SYSTEM R134a/CO2 WITH SINGLE-STAGE R404A AND TWO-STAGE CO2 INSTALLATION

The paper analyzes the electric energy consumption of three different refrigeration installations: cascade refrigeration system with R134a in the high-temperature circuit and CO2 in the low-temperature circuit, single-stage refrigeration system operating with R404A, and two-stage transcritical CO2 system. The indirect impact of the refrigeration system on global warming through electric energy consumption was examined. Thermodynamic cycles of these installations have been described and models have been developed to analyze the electric energy consumption required to drive the compressor as the largest consumer, for the cooling capacity of the evaporator 5,7 kW at evaporation temperature -30 °C for meteorological 2017, in the city of Belgrade. As a basis for comparative analysis, the existing cascade refrigeration system, which is located in the Laboratory for Thermal Science at the Faculty of Mechanical Engineering in Belgrade, was selected

COMPARATIVE ANALYSIS OF ELECTRIC ENERGY CONSUMPTION OF CASCADE SYSTEM R134a/CO2 WITH SINGLE-STAGE R404A AND TWO-STAGE CO2 INSTALLATION

The paper analyzes the electric energy consumption of three different refrigeration installations: cascade refrigeration system with R134a in the high-temperature circuit and CO2 in the low-temperature circuit, single-stage refrigeration system operating with R404A, and two-stage transcritical CO2 system. The indirect impact of the refrigeration system on global warming through electric energy consumption was examined. Thermodynamic cycles of these installations have been described and models have been developed to analyze the electric energy consumption required to drive the compressor as the largest consumer, for the cooling capacity of the evaporator 5,7 kW at evaporation temperature -30 °C for meteorological 2017, in the city of Belgrade. As a basis for comparative analysis, the existing cascade refrigeration system, which is located in the Laboratory for Thermal Science at the Faculty of Mechanical Engineering in Belgrade, was selected

ANALYSIS OF ENERGY CONSUMPTION OF A RESIDENTIAL BUILDING USING HOURLY SIMULATIONS

The largest amount of energy in Serbia households is spent on heating needs. Therefore, the main idea of this paper is to compare the heating bills for a residential building in Belgrade using various energy sources. Electric boiler, gas-fired condensing boiler, and air-to-water heat pump are analyzed. For calculating expenses, the current electricity and gas rates in Serbia have been used. For selected cases, both primary energy use and CO2 emission have been compared