Klemens Schwarzer - Academia.edu (original) (raw)
Uploads
Papers by Klemens Schwarzer
[
Proceedings of the ISES Solar World Congress 2011, 2011
2020 1st International Conference on Innovative Research in Applied Science, Engineering and Technology (IRASET), 2020
In this article, we have described the structure, operation and we present the heat transfer mode... more In this article, we have described the structure, operation and we present the heat transfer models in the different blocks of a solar thermal cooker powered by a parabolic trough concentrator equipped by a vacuum tube during a sunny day. After one hour of operation the temperature of the upper part of the pot reaches the value 168° C. Around 1 p.m. the results show that under an maximum and almost stable of global solar radiation around 720 W/m2 the maximum recorded temperatures of the small tube, large tube, center of the pot and the upper part of the pot are respectively: 370°C, 270°C, 260°C and 265° C. On the other hand test of cooking fries shown that the temperature of oil rise to 198°C after 1 hour 10 minutes of cooking and the fries are well cooked. The performance and temperatures obtained are suitable for cooking fries during this work shows the feasibility of cooking all types of food outside the hearth.
Sustainable Entrepreneurship, Renewable Energy-Based Projects, and Digitalization, 2020
This research article determines the experimental efficiency of a solar cooker with storage syste... more This research article determines the experimental efficiency of a solar cooker with storage system. This system is composed of flat plate collectors, a cooking unity, control valves and a heat storage tank. In its operation, the working fluid is heated in the solar collectors and moves in a thermal siphon circuit. The control valves direct the fluid flux to the cooking unity or to the storage tank for later use. In the experiments, the gathered data are measured by precision instruments and are stored in a data-logger. These data are used to determinate the heat sensible and boiling thermal efficiencies. The results show the good system performance, with the sensible efficiency varying from 0,34 to 0,38. The results also show that when the same tests are made with the heat stored into the tank, the heating time intervals for direct and indirect cooking are very closed. The latent efficiency varied around 0,30.
Materials Today: Proceedings, 2019
Climate change and global warming are causing sea level rise and thus the degradation of groundwa... more Climate change and global warming are causing sea level rise and thus the degradation of groundwater quality by excess salt. In this context, the purpose of this work is the establishment of a system for the remote acquisition and supervision of a multi-stage solar distiller to supply drinking water to the Douar Al Hamri in the rural district of Boughriba in the province of Berkane (Oujda Region). The system implemented will allow instantaneous monitoring the operation of the station in real time to ensure the amount and quality of produced fresh water, and remote intervention in case of failure or malfunctioning of the systems. In this paper, after describing the operation of the solar distiller, the structure of its control and supervision system is presented, including: the start-up and shutdown of the distiller, tracking of its functionality, data acquisition, and control connection to the electricity grid or photovoltaic generators.
Solar Energy, 1999
Commercial acceptance and the economics of solar thermal technologies are tied to the design and ... more Commercial acceptance and the economics of solar thermal technologies are tied to the design and development of efficient, cost-effective thermal storage systems. Thermal storage units that utilize latent heat storage materials have received greater attention in the recent years because of their large heat storage capacity and their isothermal behavior during the charging and discharging processes. One major issue that needs to be addressed is that most phase-change materials (PCM) with high energy storage density have an unacceptably low thermal conductivity and hence heat transfer enhancement techniques are required for any latent heat thermal storage (LHTS) applications. In the present paper the various heat transfer enhancement methods for LHTS systems are discussed. Three different experiments to augment heat transfer were conducted and the findings are reported.
Desalination, 2001
This work presents the energy and mass balance equations, the numerical simulation results for th... more This work presents the energy and mass balance equations, the numerical simulation results for the production rate, and the experimental laboratory water tests for a thermal desalination unit with a heat recovery system. The system components are a solar collector and a desalination tower, although the system can be operated with other energy sources. The desalination tower is made of six stages and a water circulation system through the stages to avoid salt concentration. The numerical results calculated using ambient data show that the production rate can reach 25 L/m?d, which is by a factor of five times greater than the rate of a basin-type solar desalination unit. The water (polluted seawater and well water) laboratory tests results show that the desalination process eliminated the Co&&m group bacteria and reduced the salt concentration to very low levels.
Page 1. Solare Meerwasserentsalzungsanlagen mit mehrstufiger Verdunstung -Betriebsversuche, dynam... more Page 1. Solare Meerwasserentsalzungsanlagen mit mehrstufiger Verdunstung -Betriebsversuche, dynamische Simulation und Optimierung-Dissertation zur Erlangung des Grades Doktor-Ingenieur der Fakultät für Maschinenbau der Ruhr-Universität Bochum von ...
Proceedings of the ISES Solar World Congress 2015, 2016
The objective of this research is the development, evaluation and analyzation of a new test metho... more The objective of this research is the development, evaluation and analyzation of a new test method, called "rapid test method", for fast and inexpensive assessment of concentrating collectors. The rapid test method aims to derive the instantaneous efficiency curve of a parabolic trough collector. Therefore, a new reference parabolic trough collector was designed and installed at a test rig in accordance with ISO 9806. The determination of the instantaneous efficiency curve according to the rapid test method was compared to the efficiency curve based on ISO 9806. The comparison shows that the rapid test method delivers reproducible and reliable values for the characteristic curve of linear concentrating collectors. The obtained results are within the limits of the measurement uncertainty of a characteristic curve based on ISO 9806. Therefore, the method can be regarded as reliable, inexpensive and easy to use alternative to the conventional measuring method.
Solar Energy, 2003
This article presents the recent development in manufacturing a solar cooker, with indirect heati... more This article presents the recent development in manufacturing a solar cooker, with indirect heating and with or without temporary heat storage. The two basic system components are the solar collectors with reflectors and a cooking unit. The working fluid, thermal oil, circulates in natural, thermo-siphon flow through copper piping connect the components. The system presents interesting features such as the possibility of indoor cooking, heat flow control in the pots, and modularity. The first prototype of this collector-cooker system was built and installed in Juelich, Germany. Further development and adjustment were performed for the next versions. For this work, a new flat plate collector with one plastic and one glass cover was tested and the experimental measurements show the good performance of the cooker.
Rio3 World Climate and …, 2003
This research article shows the experimental results of a solar desalination system to produce po... more This research article shows the experimental results of a solar desalination system to produce potable water for drinking purposes from either sea or salty ground water. This system has two components: a flat plate solar collector, and a desalination tower with heat recovery mechanism. The flat plate solar collector can be used in either direct or indirect heating mode. In the first case, the water that runs through the collector absorber is the condensate produced in the desalination tower. This condensate flows down on sidewall to a clean water tank at the bottom of the tower. The hot water in the tank evaporates and condenses on the walls of the first stage, directly heating the salty water in this stage. In the indirect heating, solar radiation is absorbed in the collector and transferred to a thermal oil flux, which transport this heat to a mass of salty water in the desalination tower. The heat transfer takes place in a heat exchanger at the lowest level, or the first stage in the desalination tower .Two units were built and tested, one for each heating mode. The desalination tower has six stages and a water circulation system through the stages to avoid salt concentration. The results show the good system thermal performance, and that improvements can be made to reach even higher potable water production rates. The water (polluted sea water and salty well water) laboratory test results show that the desalination process eliminated the Coliform group bacteria, being appropriated for human use.
[
Proceedings of the ISES Solar World Congress 2011, 2011
2020 1st International Conference on Innovative Research in Applied Science, Engineering and Technology (IRASET), 2020
In this article, we have described the structure, operation and we present the heat transfer mode... more In this article, we have described the structure, operation and we present the heat transfer models in the different blocks of a solar thermal cooker powered by a parabolic trough concentrator equipped by a vacuum tube during a sunny day. After one hour of operation the temperature of the upper part of the pot reaches the value 168° C. Around 1 p.m. the results show that under an maximum and almost stable of global solar radiation around 720 W/m2 the maximum recorded temperatures of the small tube, large tube, center of the pot and the upper part of the pot are respectively: 370°C, 270°C, 260°C and 265° C. On the other hand test of cooking fries shown that the temperature of oil rise to 198°C after 1 hour 10 minutes of cooking and the fries are well cooked. The performance and temperatures obtained are suitable for cooking fries during this work shows the feasibility of cooking all types of food outside the hearth.
Sustainable Entrepreneurship, Renewable Energy-Based Projects, and Digitalization, 2020
This research article determines the experimental efficiency of a solar cooker with storage syste... more This research article determines the experimental efficiency of a solar cooker with storage system. This system is composed of flat plate collectors, a cooking unity, control valves and a heat storage tank. In its operation, the working fluid is heated in the solar collectors and moves in a thermal siphon circuit. The control valves direct the fluid flux to the cooking unity or to the storage tank for later use. In the experiments, the gathered data are measured by precision instruments and are stored in a data-logger. These data are used to determinate the heat sensible and boiling thermal efficiencies. The results show the good system performance, with the sensible efficiency varying from 0,34 to 0,38. The results also show that when the same tests are made with the heat stored into the tank, the heating time intervals for direct and indirect cooking are very closed. The latent efficiency varied around 0,30.
Materials Today: Proceedings, 2019
Climate change and global warming are causing sea level rise and thus the degradation of groundwa... more Climate change and global warming are causing sea level rise and thus the degradation of groundwater quality by excess salt. In this context, the purpose of this work is the establishment of a system for the remote acquisition and supervision of a multi-stage solar distiller to supply drinking water to the Douar Al Hamri in the rural district of Boughriba in the province of Berkane (Oujda Region). The system implemented will allow instantaneous monitoring the operation of the station in real time to ensure the amount and quality of produced fresh water, and remote intervention in case of failure or malfunctioning of the systems. In this paper, after describing the operation of the solar distiller, the structure of its control and supervision system is presented, including: the start-up and shutdown of the distiller, tracking of its functionality, data acquisition, and control connection to the electricity grid or photovoltaic generators.
Solar Energy, 1999
Commercial acceptance and the economics of solar thermal technologies are tied to the design and ... more Commercial acceptance and the economics of solar thermal technologies are tied to the design and development of efficient, cost-effective thermal storage systems. Thermal storage units that utilize latent heat storage materials have received greater attention in the recent years because of their large heat storage capacity and their isothermal behavior during the charging and discharging processes. One major issue that needs to be addressed is that most phase-change materials (PCM) with high energy storage density have an unacceptably low thermal conductivity and hence heat transfer enhancement techniques are required for any latent heat thermal storage (LHTS) applications. In the present paper the various heat transfer enhancement methods for LHTS systems are discussed. Three different experiments to augment heat transfer were conducted and the findings are reported.
Desalination, 2001
This work presents the energy and mass balance equations, the numerical simulation results for th... more This work presents the energy and mass balance equations, the numerical simulation results for the production rate, and the experimental laboratory water tests for a thermal desalination unit with a heat recovery system. The system components are a solar collector and a desalination tower, although the system can be operated with other energy sources. The desalination tower is made of six stages and a water circulation system through the stages to avoid salt concentration. The numerical results calculated using ambient data show that the production rate can reach 25 L/m?d, which is by a factor of five times greater than the rate of a basin-type solar desalination unit. The water (polluted seawater and well water) laboratory tests results show that the desalination process eliminated the Co&&m group bacteria and reduced the salt concentration to very low levels.
Page 1. Solare Meerwasserentsalzungsanlagen mit mehrstufiger Verdunstung -Betriebsversuche, dynam... more Page 1. Solare Meerwasserentsalzungsanlagen mit mehrstufiger Verdunstung -Betriebsversuche, dynamische Simulation und Optimierung-Dissertation zur Erlangung des Grades Doktor-Ingenieur der Fakultät für Maschinenbau der Ruhr-Universität Bochum von ...
Proceedings of the ISES Solar World Congress 2015, 2016
The objective of this research is the development, evaluation and analyzation of a new test metho... more The objective of this research is the development, evaluation and analyzation of a new test method, called "rapid test method", for fast and inexpensive assessment of concentrating collectors. The rapid test method aims to derive the instantaneous efficiency curve of a parabolic trough collector. Therefore, a new reference parabolic trough collector was designed and installed at a test rig in accordance with ISO 9806. The determination of the instantaneous efficiency curve according to the rapid test method was compared to the efficiency curve based on ISO 9806. The comparison shows that the rapid test method delivers reproducible and reliable values for the characteristic curve of linear concentrating collectors. The obtained results are within the limits of the measurement uncertainty of a characteristic curve based on ISO 9806. Therefore, the method can be regarded as reliable, inexpensive and easy to use alternative to the conventional measuring method.
Solar Energy, 2003
This article presents the recent development in manufacturing a solar cooker, with indirect heati... more This article presents the recent development in manufacturing a solar cooker, with indirect heating and with or without temporary heat storage. The two basic system components are the solar collectors with reflectors and a cooking unit. The working fluid, thermal oil, circulates in natural, thermo-siphon flow through copper piping connect the components. The system presents interesting features such as the possibility of indoor cooking, heat flow control in the pots, and modularity. The first prototype of this collector-cooker system was built and installed in Juelich, Germany. Further development and adjustment were performed for the next versions. For this work, a new flat plate collector with one plastic and one glass cover was tested and the experimental measurements show the good performance of the cooker.
Rio3 World Climate and …, 2003
This research article shows the experimental results of a solar desalination system to produce po... more This research article shows the experimental results of a solar desalination system to produce potable water for drinking purposes from either sea or salty ground water. This system has two components: a flat plate solar collector, and a desalination tower with heat recovery mechanism. The flat plate solar collector can be used in either direct or indirect heating mode. In the first case, the water that runs through the collector absorber is the condensate produced in the desalination tower. This condensate flows down on sidewall to a clean water tank at the bottom of the tower. The hot water in the tank evaporates and condenses on the walls of the first stage, directly heating the salty water in this stage. In the indirect heating, solar radiation is absorbed in the collector and transferred to a thermal oil flux, which transport this heat to a mass of salty water in the desalination tower. The heat transfer takes place in a heat exchanger at the lowest level, or the first stage in the desalination tower .Two units were built and tested, one for each heating mode. The desalination tower has six stages and a water circulation system through the stages to avoid salt concentration. The results show the good system thermal performance, and that improvements can be made to reach even higher potable water production rates. The water (polluted sea water and salty well water) laboratory test results show that the desalination process eliminated the Coliform group bacteria, being appropriated for human use.