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Search results for: high temperature heat pumps
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HIGH TEMPERATURE HEAT PUMPS – PERSPECTIVE HEATING SYSTEMS?
PublicationIn the paper presented are authors own concepts of high temperature compressor heat pumps for the utilisation of medium and low temperature sources of heat. Working fluids for use in high temperature heat pumps are discussed, as well as the criteria for their selection. Analyses are presented for the production of in the upper steam source at 130 °C. One-stage systems and cascade systems were analyzed. An analysis of the coefficient...
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High-temperature heat pumps – potential technology for heat recovery and production of process heat
PublicationIn the paper, the high temperature vapour compressor based heat pump with a selection of working fluids, both perspective and ecological ones, is considered. Such system is not yet commercially available on the market and in author’s opinion it has significant potential for various applications. In the presented analysis it was assumed that the heat source has a temperature of 50oC and the temperature lift is 60, 80 and 100K respectively....
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High-temperature heat pumps – new devices for heat recovery and production of technological steam
PublicationIn the paper, the original high temperature compressor based heat pump with a dry working fluid, i.e. the one in which the slope of saturated vapour line is positive, was presented. The objective of the paper is to investigate the possibility of preparation of technological steam with tempperature 120 C from the waste heat resource at temperature of 50 C. Single comppression cycles as well as cascade systems have been considered...
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Numerical analysis of high temperature minichannels heat exchanger performance
PublicationNowadays, the most difficult technological challenge in energy sector is connected with the gas micro-CHP units, dedicated to the distributed power generation. They are expected to be of high efficiency and at the same time of compact in size. Regarding the first reason, significant increase in microturbine efficiency can only be achieved by increase in the engine operating temperature. Therefore, one of the critical elements in...
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Performance of the very high-temperature heat pump with low GWP working fluids
PublicationTraditional heat pumps are a very attractive pro-ecological solutions for a number of applications, including providing of heating or heat recovery from industrial processes. The application range of heat pumps could be greatly enlarged when the operating temperature would be increased to 130-150°C and/or the temperature lift can be increased to 50-100 K. In the paper, the very high temperature vapour-compressor based single stage...
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Numerical analysis of high temperature minichannel heat exchanger for recuperative microturbine system
PublicationConsidering the development of energy sector, distributed small-scale power generation, e.g., gas micro-CHP, is attracting considerable interest. In such installations, the heat exchanger is one of the key components possessing a significant influence on overall performance. Most studies concentrate on units operating below 900C, which do not fulfil the requirements of gas micro-CHP. Therefore, there remains a challenge to design...
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Influence of Heat Treatment Temperature on Fatigue Toughness in Medium-Carbon High-Strength Steels
PublicationCurrent research has demonstrated that the tempering temperature affects the martensitic transformation of medium-carbon high-strength steels. This temperature plays an important role in the final microstructure, percentage ratios of martensite to ferrite phases and, consequently, in the mechanical properties and the fatigue response. So far, the relationship between the martensitic tempering temperature and the cyclic deformation...
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High Temperature Air/Steam Conversion of Biomass and Wastes Into Fuel Gas for Heat and Electricity Production
PublicationPaper present principle of high temperature air/staem gasification as well as some results of research using this technology for conversion of biomass and wastes into fuel gas.
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Nonlinear impedance of Bi2VO5.5 glass-ceramic heat-treated at 913 K was measured with impedance spectroscopy method at high temperature region
Open Research DataThe nonlinear electrical properties of Bi2VO5.5 glass-ceramic heat-treated at 913 K was measured by impedance spectroscopy method.
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Results of implementation of Feed Forward Neural Networks for modeling of heat transfer coefficient during flow condensation for low and high values of saturation temperature
Open Research DataThis database present results of implementation of Feed Forward Neural Networks for modeling of heat transfer coefficient during flow condensation for low and high values of saturation temperature. Databse contain one table and 7 figures.
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Linear impedance of 50(2Bi2O3-V2O5)-50SrB4O7 glass heat treated at 693 K measured with impedance spectroscopy method at high temperature region
Open Research DataThe linear electrcial properties of 50(2Bi2O3-V2O5)-50SrB4O7 glass heat treated at 693 K was measured by impedance spectroscopy method.
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Nonlinear impedance of 50(2Bi2O3-V2O5)-50SrB4O7 glass heat treated at 693 K measured with impedance spectroscopy method at high temperature region
Open Research DataThe nonlinear electrcial properties of 50(2Bi2O3-V2O5)-50SrB4O7 glass heat treated at 693 K was measured by impedance spectroscopy method.
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Nonlinear impedance of 50(2Bi2O3-V2O5)-50SrB4O7 glass heat treated two times measured with impedance spectroscopy method at high temperature region
Open Research DataThe nonlinear electrcial properties of 50(2Bi2O3-V2O5)-50SrB4O7 glass heat treated two times was measured by impedance spectroscopy method.
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Linear impedance of 50(2Bi2O3-V2O5)-50SrB4O7 glass-ceramic heat-treated at 613 K measured with impedance spectroscopy method at high temperature region
Open Research DataThe linear electrcial properties of 50(2Bi2O3-V2O5)-50SrB4O7 glass-ceramic heat-treated at 613 K was measured by impedance spectroscopy method.
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Nonlinear impedance of 50(2Bi2O3-V2O5)-50SrB4O7 glass-ceramic heat-treated at 813 K measured with impedance spectroscopy method at high temperature region
Open Research DataNonlinear electrcial properties of 50(2Bi2O3-V2O5)-50SrB4O7 glass-ceramic heat treated at 813 K was measured by impedance spectroscopy method.
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Nonlinear impedance of 50(2Bi2O3-V2O5)-50SrB4O7 glass-ceramic heat-treated at 613 K measured with impedance spectroscopy method at high temperature region
Open Research DataNonlinear electrcial properties of 50(2Bi2O3-V2O5)-50SrB4O7 glass-ceramic heat treated at 613 K was measured by impedance spectroscopy method.
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Nonlinear impedance of Bi2VO5.5 ceramic of thickness 2.52 mm (after second heat-treatment at 913 K) was measured at high temperature range with impedance spectroscopy method
Open Research DataThe nonlinear electrical properties of Bi2VO5.5 ceramic of thickness 2.52 mm (after second heat-treatment at 913 K) was measured by impedance spectroscopy method.
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Linear impedance as a function of A.C. voltage for 50(2Bi2O3-V2O5)-50SrB4O7 glass-ceramic heat-treated at 813 K measured with impedance spectroscopy method at high temperature region
Open Research DataThe linear electrcial properties as a function of A.C. voltage of 50(2Bi2O3-V2O5)-50SrB4O7 glass-ceramic heat treated at 813 K was measured by impedance spectroscopy method.
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Influence of the low ambient temperature on the start-up process of hydraulic pumps
PublicationStarting hydraulic pumps in low ambient temperatures may cause: decreased hydraulic-mechanical efficiency, larger vibration of hydraulic installation, faster wear and more frequent damage to the elements of pumps, change of material properties of elements, increase of pressure drop. As a result of pressure drop in the suction pipe, large underpressure may be experienced, causing incomplete filling of pump working chambers with...
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Utilisation of bleed steam heat to increase the upper heat source temperature in low-temperature ORC
PublicationW pracy przedstawiono możliwość dogrzewu obiegu ORC za pomocą pary upustowej.
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Management of low-temperature heat source by ORC aided by additional heat source
PublicationIn the paper presented is a concept to utilize waste heat from the power plant with the aid of the low-temperature ORC cycle. The ORC system is heated from two heat sources, the first one being the flow rate of waste heat obtained from the exhaust gases. Subsequently, the working fluid in the cycle is additionally heated by the condensing steam from the low pressure turbine extraction points increasing in such way the level of...
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Management of low-temperature heat source by ORC aided by additional heat source
PublicationThe presented work is aimed at utilisation of waste heat in the manner to produce electricity in ORC installation. Therefore the precondition of the study was to use the waste heat available in the form of a stream of hot water at 90°C. Such low enthalpy heat source is rather insufficient to produce a good quality vapour to feed the ORC turbine. That was the incentive to search for the ways of increasing the temperature of the...
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Pressure drop and heat transfer during boiling and condensation at subcritical region
PublicationMost of the data presented in the literature relate to saturation temperatures in the range - 20°C to 40°C due to the application in refrigeration technology. There is necessity to extend databases to higher values of saturation temperature due to new applications such as Organic Rankine Cycle and high temperature heat pumps. Only few papers contain data for high reduced pressure for low boiling point liquids. This paper focus...
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Ewa Klugmann-Radziemska prof. dr hab.
PeopleEwa Klugmann-Radziemska graduated from the University of Gdansk with a degree in physics, and since 1996 has been associated with the Gdansk University of Technology, when she began PhD studies. Currently, he is a professor at the Faculty of Chemistry at the Gdansk University of Technology, since 2006 head of the Department of Chemical Apparatus and Machinery. In the years 2008–2016 she was the Vice-Dean for cooperation and development,...
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Application of Feed Forward Neural Networks for Modeling of Heat Transfer Coefficient During Flow Condensation for Low and High Values of Saturation Temperatur
PublicationMost of the literature models for condensation heat transfer prediction are based on specific experimental parameters and are not general in nature for applications to fluids and non-experimental thermodynamic conditions. Nearly all correlations are created to predict data in normal HVAC conditions below 40°C. High temperature heat pumps operate at much higher parameters. This paper aims to create a general model for the calculation...
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The effect of temperature difference on heat transport in solar cells
PublicationW pracy omówiono wpływ wzrostu temperatury i mechanizm transportu ciepła na drodze przewodzenia w układach hybrydowych PV/T. Wyznaczono współczynniki przewodzenia krystalicznego krzemu typu n i p oraz gęstość strumienia ciepła w zakresie temperatur od 0 do 100 st. C.
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Effect of Temperature and Nanoparticle Concentration on Free Convective Heat Transfer of Nanofluids
PublicationA theoretical analysis of the influence of temperature and nanoparticle concentration on free convection heat transfer from a horizontal tube immersed in an unbounded nanofluid was presented. The Nusselt (Nu) number and heat transfer coefficient were parameters of the intensity of the convective heat transfer. For free convection, the Nu number was a function of the Rayleigh (Ra) number and Prandtl (Pr) number. The Rayleigh (Ra)...
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The low temperature waste heat recovery in drying process of pine wood using micro-jet heat exchanger
PublicationThe article presents the influence of the drying medium temperature changes for the relative and absolute moisture content values during pine wood drying. The drying process was conducted at constant atmospheric pressure and with different drying medium (air) temperature levels, respectively: 40oC, 60oC, 80oC, 100oC, and 120oC. In order to develop a method that would enable low temperature drying of solid materials the experiments...
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Metal-organic frameworks (MOF) based heat transfer: A comprehensive review
PublicationHigher than a standard level, the humidity provides a suitable environment for the pathogenic microorganisms to grow and increases energy consumption for cooling, increasing greenhouse gas emissions. Desiccant air-conditioning (DAC) is an effective method to reduce humidity and energy simultaneously. Conventional desiccants are not suitable for use as a desiccant in building air conditioners, mainly because of high regeneration...
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Recuperator with microjet technology as a proposal for heat recovery from low-temperature sources
PublicationA tendency to increase the importance of so called dispersed generation, based on the local energy sources and the working systems uti- lizing both the fossil fuels and the renewable energy resources is observed nowadays. Generation of electricity on industrial or domestic scale together with production of heat can be obtained for example through employment of the ORC systems. It is mentioned in the EU directive 2012/27/EU for...
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Recuperator with microjet technology as a proposal for heat recovery from low-temperature sources
PublicationA tendency to increase the importance of so called dispersed generation, based on the local energy sources and the working systems utilizing both the fossil fuels and the renewable energy resources is observed nowadays. Generation of electricity on industrial or domestic scale together with production of heat can be obtained for example through employment of the ORC systems. It is mentioned in the EU directive 2012/27/EU for cogenerative...
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Numerical simulation of temperature distribution of heat flow on reservoir tanks connected in a series
PublicationThe flow of temperature distribution through a medium in thermodynamic studies plays an important role in understanding physical phenomena in chemical science and petroleum engineering, while temperature distribution indicates the degree of reaction that must be undergone to obtain the final product. Therefore, this paper aims to present and apply the exponential matrix algorithm (EMA), differential transformation algorithm (DTA),...
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Impact of Temperature and Nanoparticle Concentration on Turbulent Forced Convective Heat Transfer of Nanofluids
PublicationTheoretical analysis of the influence of nanoparticles and temperature on the average Nusselt (Nu) number and the average heat transfer coefficient (HTC) during the turbulent flow of nanofluid in a horizontal, round tube was carried out. The Nu number is a function of the Reynolds (Re) number and the Prandtl (Pr) number, which in turn are functions of the thermophysical properties of the liquid and the flow conditions. On the other...
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Analytical method for calculation of heat source temperature drop for the Organic Rankine Cycle application
PublicationIn the paper presented are considerations on the cooperation of the limited capacity heat source with the Organic Rankine Cycle unit. Usually the heat source providing thermal energy to the Organic Rankine Cycle (ORC) may have twofold characteristics. It can be in the form of a single phase fluid, i.e. as hot exhaust gas or hot liquid, or in some cases it may be available as a phase changing fluid, as for example, technological...
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Finding Temperature Distribution at Heat Recovery Unit Using Genetic Algorithms
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Challenges in operating and testing loop heat pipes in 500–700 K temperature ranges
PublicationThe potential applications of loop heat pipes (LHPs) are the nuclear power space systems, fuel cell thermal management systems, waste heat recovery systems, medium temperature electronic systems, medium temperature military systems, among others. Such applications usually operate in temperature ranges between 500–700 K, hence it is necessary to develop an LHP system that will meet this requirement. Such a thermal management device...
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Numerical Investigation of Nuclear Reactor Kinetic and Heat Transfer Fractional Model with Temperature Feedback
PublicationAbstract—In the paper, the numerical results concerning the kinetics and proposed heat exchange models in nuclear reactor based on fractional calculus are presented for typical inputs. Two fractional models are proposed and compared with the model based on ordinary derivative. The first fractional model is based on one of the generalized Cattaneo equations. The second one is based on replacing the ordinary to fractional order of...
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Charakterystyka eksploatacyjna pomp ciepła zainstalowanych w oczyszczalni ścieków
PublicationW artykule przedstawiono charakterystykę eksploatacyjną sprężarkowych pomp ciepła zainstalowanych w oczyszczalni komunalnej i wykorzystujących ścieki oczyszczone jako dolne źródło ciepła. Zastosowanie ścieków oczyszczonych jest uzasadnione ich dostępnością oraz stosunkowo wysoką temperaturą (10-25°C). Prawidłowa eksploatacja układu wymaga zastosowania pośredniego obiegu parowacza oraz regularnych zabiegów czyszczenia wymiennika...
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Influence of wall temperature on heat transfer coefficient during R 22 boiling in microfin tube
PublicationPrzedstawiono wyniki badań współczynnika przejmowania ciepła i spadku ciśnienia podczas wrzenia czynnika R 22 w rurze nisko żebrowanej. Opisano stanowisko i procedurę badawczą. Zaobserwowano spadek współczynnika przejmowania. Opisano stanowisko i procedurę badawczą. Zaobserwowano spadek współczynnika przejmowania ciepła wraz ze wzrostem temperatury ścianki rury.
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Comparison of traditional district heating with low temperature district heating systems featuring organic Rankine cycle and heat pump
PublicationPaper presents a comparison between a traditional district heating system with conventional boilers as a source of heat and electricity purchases from power utilities and a low temperature DH system incorporating the CHP with organic Rankine Cycle providing electricity and local heat pump raising the temperature of the DH fluid to the required temperature in the dwelling, meaning that both heat and electricity are produced within...
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Funkcjonowanie zespołów napędu hydraulicznego maszyn w niskich temperaturach otoczenia
PublicationW pracy przedstawiono cztery warianty klasyfikacji rozruchów oziębionego napędu hydraulicznego. Pierwsza sytuacja dotyczy zagadnienia, w którym wszystkie zespoły układu napędowego wraz z olejem mają taką samą niską temperaturę podczas rozruchu. Pozostałe warianty odnoszą się do rozruchu w warunkach szoku termicznego wywołanych zasilaniem ciepłym czynnikiem roboczym oziębionych zespołów hydraulicznych. Rozruch zespołów...
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RESEARCH OF HYDRAULIC PISTON PUMPS’ START-UP IN LOW AMBIENT TEMPERATURES
PublicationStarting hydraulic pumps in low ambient temperatures may cause: decreased hydraulic-mechanical efficiency, larger vibration of hydraulic installation, faster wear and more frequent damage to the elements of pumps, change of material properties of elements, increase of pressure drop. As a result of increase of resistance of cold oil flow in the suction pipe, large underpressure may be experienced, causing incomplete filling of pump...
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Volumetric and torque efficiency of pumps during start-up in low ambient temperatures
PublicationThe volumetric, torque and total efficiency of hydraulic pumps change during start-up in low ambient temperatures, as well as in thermal shock conditions, un-til they reach the set conditions. The time to reach steady-state conditions de-pends on many parameters: ambient temperature, flow rate, fluid temperature, design of hydraulic units. The author carried out tests of hydraulic pumps in the Hydraulics Laboratory of the Faculty...
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New satellite pumps
PublicationStosowanie Maszyn company from Katowice was initiator and originator of newest original high pressure satellite pumps series of types PSM. Construction solution, research and development of these pumps have been conducted by Team of Hydraulics and Pneumatics of Gdansk University of Technology in cooperation with this company within the confines of research project nr R0300103 (source of funds: Ministry of Science and Higher Education)....
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Influence of Gaps’ Geometry Change on Leakage Flow in Axial Piston Pumps
PublicationAxial piston pumps are the core elements of most medium and high-pressure hydraulic systems. High volumetric efficiency and high working pressures are the main advantages of this type of pumps. Therefore it is necessary to accurately calculate the leakage flow through the gaps to design efficient high-pressure pump. The main difficulty of such calculations is the fact, that the gaps change their geometry during pumping process....
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Compensation of pressure peaks in pwk-type hydraulic pumps
Publicationhydraulic axial pumps equipped with cam-driven commutation unit (pwk pumps) proved their high efficiency up to 55 mpa and ability to work self-sucking, even at high speed. displacement of pwk pump may easily be changed by moving its control cam. full discharge from hydrostatic forces makes such control possible by direct action of a low-energy actuator like proportional electromagnet or stepping motor. that eliminates heavy and...
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Protection System Design of Induction Motor for Industries
PublicationThe fundamental and durable structures of induction motor, as well as their low manufacturing cost, make them popular components in a wide range of current applications. Providing a safety net for employees is a must-have for businesses. This project’s motivation for improvement is to provide industrial motors, lift motors, pumps, and so on with safety. An induction motor’s primary goal is to protect it from problems, such as...
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Protection System Design of Induction Motor for Industries
PublicationThe fundamental and durable structures of induction motor, as well as their low manufacturing cost, make them popular components in a wide range of current applications. Providing a safety net for employees is a must-have for businesses. This project’s motivation for improvement is to provide industrial motors, lift motors, pumps, and so on with safety. An induction motor’s primary goal is to protect it from problems, such as...
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STUDY ON THE EFFECTIVENESS OF THE TURBINE CONDENSER AIR EXTRACTION SYSTEM USING HYDRO EJECTORS
PublicationThe aim of the paper is to investigate the effectiveness of the 18K380 steam turbine condenser air extraction system using hydro ejectors. Motivation for the analysis is a need of improvement of the energy conversion ratio of the power plant. To achieve this goal it is necessary to establish efficiency of each subsystem of the energy cycle. The air extraction system is not a highly power consuming system but it has great impact...
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Jan Wajs dr hab. inż.
People