DSpace Collection:
http://hdl.handle.net/20.500.12188/161
2024-03-29T12:55:44ZHVAC&R POLY-GENERATION SYSTEM WITH A GAS ENGINE AND CONVENTIONAL COOLING MACHINES/HEAT PUMPS
http://hdl.handle.net/20.500.12188/29741
Title: HVAC&R POLY-GENERATION SYSTEM WITH A GAS ENGINE AND CONVENTIONAL COOLING MACHINES/HEAT PUMPS
Authors: Gjerasimovski, Aleksandar; Sharevska, Maja; Gjerasimovska, Nataša; Sharevska, Monika; Šarevski, Vasko
Abstract: A new concept of poly-generation system for simultaneous production of electricity, heating, and cooling energy for HVAC&R of buildings is presented in this paper. The thermal characteristics of buildings and systems, the performance parameters of the gas engine–electricity generator and of the heating and cooling units (heat pumps/cooling machines) are analyzed. The original purpose of the gas engine–electricity generator is to supply the units for production of heating and cooling energy. Waste heat from the internal combustion engine is used primarily for production of hot water for the central heating system and/or production of sanitary hot water, and secondarily as a heat source in the conventional heat pump. A comparison of the energy (gas) consumption with conventional thermal system is made and high energy efficiency of the proposed system is confirmed.2022-12-01T00:00:00ZExperimental Research of the Mechanical Properties of the Injection Molded Parts in Molds Produced By Additive Manufacturing
http://hdl.handle.net/20.500.12188/29704
Title: Experimental Research of the Mechanical Properties of the Injection Molded Parts in Molds Produced By Additive Manufacturing
Authors: Tuteski, Ognen; Kochov, Atanas
Abstract: In this study, additive manufacturing emerges as an innovative technology for concurrent engineering in the design and production of molds for injection molding processes. The primary objective is to conduct experimental research on the mechanical properties of injection-molded parts using a non-conventional mold produced through additive manufacturing technologies. The state-of-the-art additive manufacturing technologies provide various methodologies and techniques for designing and printing parts. Utilizing these diverse technologies significantly expands the possibilities for rapidly creating molds, thereby enhancing the scope of rapid tooling in the molding process. The study begins by designing and fabricating SLA mold inserts according to the relevant tensile testing standards. To evaluate the mechanical properties, a series of tensile tests are conducted and a comparison is made between the properties of the molded parts produced with SLA mold inserts. The results demonstrate that SLA mold inserts made with additive manufacturing can effectively produce injection molded parts with comparable tensile strength to those manufactured using traditional steel molds.2023-01-01T00:00:00ZIoT System for Real-Time Water Quality Measurement and Data Visualization
http://hdl.handle.net/20.500.12188/29286
Title: IoT System for Real-Time Water Quality Measurement and Data Visualization
Authors: Radmila Koleva; Emil Zaev; Darko Babunski; Gerhard Rath; Dimitar Ninevski
Abstract: A prototype of a cheap IoT system for real-time
monitoring of river water quality has been developed. The system
consists of monitoring stations and appropriate presentation
devices (computer, phone, or similar). Each monitoring station has
a possibility for real-time measurement of 4 parameters:
temperature, pH, turbidity, and dissolved oxygen. They are
measured through probes submerged directly in the water. The
probes are connected to the Raspberry Pi 3 model B, and through
wi-fi communication, the measured data are transferred to the
data storage cloud and then transferred to the visualization
platform. The collected data in the IoT system is calculated and
presented in real-time. Using real-time we can have instant
information on the water quality and an alarm for possible
contamination. Collected data on the remote server station can be
used for deeper water quality analysis.2023-06-06T00:00:00ZENERGY EFFICIENCY OF INDUSTRIAL CONCENTRATORS WITH EJECTOR THERMOCOMPRESSION
http://hdl.handle.net/20.500.12188/29096
Title: ENERGY EFFICIENCY OF INDUSTRIAL CONCENTRATORS WITH EJECTOR THERMOCOMPRESSION
Authors: Gjerasimovski, Aleksandar; Gjerasimovska, Nataša; Šarevski, Vasko
Abstract: Research on the energy characteristics of systems with ejector thermocompression applied in industrial concentrators is presented in this paper. Ejector thermocompression achieves a significant increase in energy efficiency. The heat pump cycle in ejectors is realized through the compression of a portion of the waste steam from the solution being concentrated, which, together with motive steam from a boiler or another heat generator, is used as the driving steam for the concentration process. Thermocompression realized with thermal energy can represent a sig-nificant advantage over mechanical thermocompression. A setup for the production of concentrated sodium hydroxide (NaOH) solution with two ejector thermocompressors is presented, as well as a polygeneration system with a gas engine – electricity generator, and an ejector thermocompression system. The proposed solutions have high energy efficiency. By implementing thermocompression systems in the production of concentrates, the energy production costs are sig-nificantly reduced, which positively affects the cost of the produced concentrate. The surplus of electrical energy, as well as steam not used in the thermocompression processes, is used to supply energy for the needs of consumers in the production facilities.2023-12-31T00:00:00Z