Heat transfer research on enhanced heating surfaces in pool boiling

The paper focuses on the analysis of the enhanced surfaces in such applications as boiling heat transfer. The testing measurement module with enhanced heating surfaces was used for pool boiling research. Pool boiling experiments were conducted with distilled water at atmospheric pressure in the vessel using an enhanced sample as the bottom heating surface. The samples are soldered to a copper heating block of the round cross-section .They were placed: in the fluid (saturation temperature measurement), under the sample for temperature determination. A vessel made of four flat glass panes was used for visualization. The heated surfaces in contact with the fluid differed in roughness were smooth or enhanced. This paper analyzes the effects of the microstructured heated surface on the heat transfer coefficient. The results are presented as relationships between the heat transfer coefficient and the heat flux and as boiling curves. The experimental data obtained for the two types of enhanced heated surfaces was compared with the results recorded for the smooth heated surface. The highest local values of the heat transfer coefficient were reported for the enhanced surfaces

Using the adsorption chillers for waste heat utilisation from the CCS installation

Worldwide tendencies in the scope of environmental protection demonstrate the requirement for the limited carbon dioxide emission, that influences on the development of greenhouse effect. As a result of coal as a basic fuel used in the professional power industry, this industry sector is the greatest CO2 polluter and it means that works on the reduction of carbon dioxide in such industry are completely justified. In the IPSEpro programming environment, a reference block model for a conventional coal power station was elaborated, including the CO2 separation unit basing on the adsorption methods with the CO2 preparation installation to liquid state. Simulation researches were conducted with means of numeric techniques, that enabled the system analysis for the CO2 separation unit with the CO2 preparation system to the liquid state, as well as analysis was made for the use of chiller systems, basing on the adsorption technology for waste heat use originating from the compression of CO2 in a cascade system, as well as for potential opportunities for further exploitation of the produced chilled water in the CCS cycle. We analysed in these papers the opportunities for chiller systems application, based on the adsorption chillers in the CCS installation used for the reduction of CO2 emission in the coal power station and its influence on the operation of a power station cycle

Adsorption bed configurations for adsorption cooling application

Important parameters used for adsorption chillers, e.g. cooling capacity, coefficient of performance, are strictly dependent on heat and mass transfer conditions between adsorbent mass and the cooling/heating medium. With the aim of energy efficiency increasing it is essential to reduce heat transfer resistance. Different bed configurations and heat exchangers constructions are recommended for adsorption bed application. In the paper the review of commonly used adsorption bed configurations, i.e. loose-grain beds or fixed beds, is presented. Also, different heat exchangers for adsorption technology were described. The characteristic features of commonly applied constructions, both for commercial use and scientific research, were presented. The experimental studies presented in the literature were investigated and the substantial conclusions from the literature review are mentioned. Also, the proposition of new adsorption bed construction using the binder and additives was mentioned

Możliwości wykorzystania małych układów kogeneracyjnych w instalacjach Prosumenckich

W niniejszej pracy zaprezentowano możliwości zastosowania małych układów kogeneracyjnych do produkcji energii elektrycznej i ciepła łącznie, na przykładzie Laboratorium Układów Kogeneracji (LUK) w Centrum Energetyki - AGH oraz możliwości badawcze laboratorium LUK

Transitional Phenomena on Phase Change Materials

One of the most significant problem with technology development is transferring of large heat fluxes, which requires constant heat transfer temperature (in the specified temperature range). This problem concern mainly the nuclear energetics, space technologies, military technologies and most of all electronics containing integrated circuits with very large scale of integrations. Intensive heat transfer and thermal energy storage are possible by the use of phase change materials (PCMs). In the paper there are presented preliminary results of research on the use of liquid-gas (L-G PCMs) and solid-solid phase change materials (S-S PCMs). For L-G PCMs the boiling characteristics were determined by increasing and decreasing the heat flux, which for certain sets of structural parameters of the heating surface and the physical properties of the liquid induce a variety of forms of transitional phenomena. Thermal energy storage is much more effective when using PCMs than sensible heat

Transitional Phenomena on Phase Change Materials

One of the most significant problem with technology development is transferring of large heat fluxes, which requires constant heat transfer temperature (in the specified temperature range). This problem concern mainly the nuclear energetics, space technologies, military technologies and most of all electronics containing integrated circuits with very large scale of integrations. Intensive heat transfer and thermal energy storage are possible by the use of phase change materials (PCMs). In the paper there are presented preliminary results of research on the use of liquid-gas (L-G PCMs) and solid-solid phase change materials (S-S PCMs). For L-G PCMs the boiling characteristics were determined by increasing and decreasing the heat flux, which for certain sets of structural parameters of the heating surface and the physical properties of the liquid induce a variety of forms of transitional phenomena. Thermal energy storage is much more effective when using PCMs than sensible heat

Visualization and research of gas-liquid two phase flow structures in cylindrical channel

Two-phase flows are commonly found in many industries, especially in systems, where efficient and correct functioning depend on specific values of flow parameters. In thermal engineering and chemical technology the most popular types of two-phase mixture are gas-liquid or liquid-vapour mixtures. Bubbles can create in flow different structures and determine diverse properties of flow (velocity of phase, void fraction, fluctuations of pressure, pipe vibrations, etc.). That type of flow is difficult to observe, especially in liquid-vapour mixture, where vapour is being made by heating the medium. Production of vapour and nucleation process are very complicated issues, which are important part of two-phase flow phenomenon. Gas-liquid flow structures were observed and described with figures, but type of structure depends on many parameters. Authors of this paper made an attempt to simulate gas-liquid flow with air and water. In the paper there was presented specific test stand built to observe two-phase flow structures, methodology of experiment and conditions which were maintained during observation. The paper presents also the structures which were observed and the analysis of results with reference to theoretical models and diagrams available in literature

Pierwsza polska mobilna stacja tankowania wodoru

W artykule przedstawiono pierwszą w Polsce mobilną stację tankowania wodoru, będącą propozycją rozwiązania problemu braku infrastruktury tankowania wodoru w Polsce. W oparciu o analizę stanu techniki i aktualnych potrzeb w zakresie rozwoju elektromobilności, podjęto próbę zbudowania innowacyjnej instalacji. Opisano koncepcję konstrukcji stacji, zasadę działania stacji, wyniki testów oraz osiągnięte parametry pracy. Przedstawiono proces tankowania wodoru i obsługi stacji

Experimental Validation of the Thermal Processes Modeling in a Solar Still

Passive solar distillation is cheap and energy-efficient technology but its main disadvantage is low productivity. Thus, there are many attempts to improve solar stills’ productivity, and one of them is changing the mass of the water. This paper presents the results of validation of the thermal processes modeling in a solar still (SS). In order to validate the model, the experimental studies were conducted in a laboratory to ensure uniform climatic conditions. The studies were carried out for 10 kg, 15 kg, and 20 kg of water under three different solar irradiance conditions. The results show that 10 kg and 20 kg of water ensure the highest and the lowest daily productivity, respectively, independently of solar irradiance. When the water mass is 10 kg, the solar still’s productivity is 800 mL/m2/day, 3732 mL/m2/day, and 9392 mL/m2/day for low, medium, and high solar irradiance, respectively. Additionally, it is found that reducing the water mass from 20 kg to 10 kg can improve solar still’s productivity by a maximum value of 21.6%, which is obtained for low solar irradiance. The proposed mathematical model allows predicting the performance of the SS. The results of the theoretical calculations are in good agreement with the results of the experiments. The minimum and maximum deviation between the actual and theoretical productivity of the SS is 1.1% and 8.3%, respectively