Dynamic simulation tool for a performance evaluation and sensitivity study of a parabolic trough collector system with concrete thermal energy storage

Plant developers of parabolic trough collector (PTC) systems for industrial steam generation face various challenges. Some of the main challenges are availability of land, buildings in the vicinity of the plant that cast shadows on the collectors as well as land restrictions. The typical north-south collector axis alignment in many cases may not be possible due to limits of available ground. These were challenges that were faced in the planning phase for installing a PTC plant on the premises of the KEAN Soft Drinks Ltd factory in Limassol, Cyprus. As these issues cannot be avoided they must be accounted for by the plant developer, especially when a performance guarantee is given. This work presents, amongst other things, factors that should be analysed in order to predict the energy yield in the planning phase as best as possible by using a simulation model. In the sensitivity study presented in this paper, several effects on the energy yield were investigated theoretically. These effects include: Tracking inaccuracy, non-parallel collector row axis orientations as well as north-south vs. east-west collector alignment. A dynamic simulation model developed by the Solar-Institut Jülich (SIJ) [1] was further developed and used for the analysis. The simulation model features a deviation between the measured and simulated oil temperature at the collector outlet of only 1.5 K (rms). The findings are presented in this paper and give an insight into the effectiveness of mid-sized PTC systems for the industry sector

Operational experience and behaviour of a parabolic trough collector system with concrete thermal energy storage for process steam generation in Cyprus

As part of the transnational research project EDITOR, a parabolic trough collector system (PTC) with concrete thermal energy storage (C-TES) was installed and commissioned in Limassol, Cyprus. The system is located on the premises of the beverage manufacturer KEAN Soft Drinks Ltd. and its function is to supply process steam for the factory’s pasteurisation process [1]. Depending on the factory’s seasonally varying capacity for beverage production, the solar system delivers between 5 and 25 % of the total steam demand. In combination with the C-TES, the solar plant can supply process steam on demand before sunrise or after sunset. Furthermore, the C-TES compensates the PTC during the day in fluctuating weather conditions. The parabolic trough collector as well as the control and oil handling unit is designed and manufactured by Protarget AG, Germany. The C-TES is designed and produced by CADE Soluciones de Ingeniería, S.L., Spain. In the focus of this paper is the description of the operational experience with the PTC, C-TES and boiler during the commissioning and operation phase. Additionally, innovative optimisation measures are presented

The shrines and rock-inscriptions of Ibrîm

"Egypt Exploration Society in collaboration with Brown University"--Half t.p.Includes bibliographical references and indexes.Electronic reproduction.xii, [114] p., [49] leaves of plates ill., maps, plans 32 c

Gebel es-Silsilah, Part 1, The shrines

Includes index."Egypt Exploration Society in collaboration with Brown University"--Half t.p.Electronic reproduction.xi, 105 p., 75 leaves of plates ill., maps, plans 32 c

Chemical evolution in the environment of intermediate mass young stellar objects NGC 7129 - FIRS 2 and LkHα 234

We have carried out a molecular survey of the Class 0 IM protostar NGC 7129 - FIRS 2 (hereafter FIRS 2) and the Herbig Be star LkHα 234 with the aim of studying the chemical evolution of the envelopes of intermediate-mass (IM) young stellar objects (YSOs). The two objects have similar luminosities (∼500 L⊙) and are located in the same molecular cloud which minimizes the chemical differences due to different stellar masses or initial cloud conditions. Moreover, since they are located at the same distance, we have the same spatial resolution in both objects. A total of 17 molecular species (including rare isotopes) have been observed in both objects and the structure of their envelopes and outflows has been determined with unprecedent detail. Our results show that the protostellar envelopes are dispersed and warmed up during the evolution of the YSO into a pre-main sequence star. In fact, the envelope mass decreases by a factor >5 from FIRS 2 to LkHα 234, while the kinetic temperature increases from ∼13 K to 28 K. On the other hand, there is no molecular outflow associated with LkHα 234. The molecular outflow seems to stop before the star becomes visible. These physical changes strongly affect the chemistry of their envelopes. The N2H+ and NH3 abundances seem to be quite similar in the two objects. However, the H13CO+ abundance is a factor of ∼3 lower in the densest part of FIRS 2 than in LkHα 234, very likely because of depletion. In contrast, the SiO abundance is larger by a factor of ∼ 100 in FIRS 2 than in LkHα 234. CS presents complex behavior since its emission arises in different envelope components (outflow, cold envelope, hot core) and could also suffer from depletion. The CH3OH and H2CO column densities are very similar in FIRS 2 and LkHα 234 which implies that the beam-averaged abundances are a factor >5 larger in LkHα 234 than in FIRS 2. The same is found for the PDR tracers CN and HCN which have similar column densities in both objects. Finally, complex behavior is found for the deuterated compounds. While the DCO+/H13CO+ ratio decreases by a factor of ∼4 from FIRS 2 to LkHα 234, the D 2CO/H2CO ratios is within a factor 1.5 in both objects. The detection of a warm CH3CN component with Tk > 63 K shows the existence of a hot core in FIRS 2. Thus far, only a handful of hot cores have been detected in low and intermediate mass stars. Based on our results in FIRS. 2 and LkHα 234, we propose some abundance ratios that can be used as chemical clocks for the envelopes of IM YSOs. The SiO/CS, CN/N 2H+, HCN/N2H+, DCO +/HCO+ and D2CO/DCO+ ratios are good diagnostics of the protostellar evolutionary stage.AYA2003-07584DGI/SEPCT ESP2003-049574.223 JCR (2005) Q1, 10/46 Astronomy & AstrophysicsUE

Photon dominated chemistry in the nucleus of M82: Detection of HOC + in a starburst galaxy

The nucleus of M82 has been mapped in 3mm and 1mm lines of CN, HCN, C 2H, c-C3H2, CH3C2H, HC3N and HOC+ using the IRAM 30m telescope. These species have been selected for constituting a good diagnostic of photon-dominated chemistry. We have measured [CN]/[HCN] ratios ≥ 5 in the inner 650 pc galaxy disk. Furthermore, we have detected the HOC+ 1→0 line with an intensity similar to that of the H13CO+ 1→0 line. This implies a [HCO+]/[HOC+] ratio of ∼ 40. This low HCO+/HOC+ abundance ratio unambiguously shows that the chemistry of the molecular gas reservoir in the nucleus of M82 is determined by the intense interstellar UV flux (G0 ∼ 104 in units of Habing field). Finally, the detection of the hydrocarbons c-C3H 2 and CH3C2H in the nucleus of M82 suggests that a complex carbon chemistry is developing in this giant photo-dissociation region (PDR).Ministerio de Ciencia y Tecnología DGES/AYA2000-927Ministerio de Ciencia y Tecnología ESP2001-4519-PEMinisterio de Ciencia y Tecnología ESP2002-01693No data (2005)UE

Chemical study of the giant PDR in the nucleus of M82: Detection of HOC+ in a starburst galaxy

The nucleus of M82 has been mapped in 3mm and 1mm lines of ON, HCN, C 2H, c-C3H2, CH3C2H, HC3N and the HOC+ using the IRAM 30m telescope. These species have been selected for constituting a good diagnostic of photon-dominated chemistry. We have measured [CN]/[HCN] ratios ≥ 5 in the inner 650 pc galaxy disk. Furthermore, we have detected the HOC+ 1→K) line with an intensity similar to that of the H13CO + 1→0 line. This implies a [HCO+]/[HOC+] ratio of ∼ 40. This low [HCO+]/[HOC+] ratio shows that the chemistry of the molecular gas reservoir in the nucleus of M82 is heavily influenced by the intense UV flux (G0 ∼ 104 in units of Habing field). Finally, the detection of the hydrocarbons c-C 3H2 and CH3C2H in the nucleus of M82 suggests that a complex carbon chemistry is developing in this giant photo-dissociation region (PDR).Sin financiación0.112 SJR (2005) Q4, 88/150 Aerospace engineering, 69/82 Space and planetary scienceUE

Dynamic simulation model of a parabolic trough collector system with concrete thermal energy storage for process steam generation

Published AIP Conference Proceedings, 2019, Volume 2126, Article number 150007Parabolic trough collector (PTC) systems are commercially available concentrating solar power plants widely known for their application to generate electrical power. To further reduce the dependency on fossil fuels, such systems can also be deployed for producing process heat for industrial purposes. In combination with a thermal energy storage system, this technology has the ability to reliably supply on-demand process heat. This paper gives details on a fully automated PTC system with concrete thermal energy storage (C-TES) and kettle-type boiler that supplies saturated steam for a beverage factory in Limassol, Cyprus. In the focus is the validation of a dynamic simulation model in Modelica® that physically describes the entire PTC system. The simulation model uses various plant data as inputs including mirror reflectivity and weather data from on-site measurements. The validation was carried out in three steps. First, the PTC was validated as a stand-alone component. A time-dependent inlet oil temperature vector was given as input and the outlet oil temperature was computed. The root mean square (rms) error between the measured to simulated outlet oil temperature values results in 3.86 % (equivalent to about 1.9 K). The second part of the validation then considered a complete PTC oil cycle in PTC-and-boiler operation mode (without C-TES). In the simulation, both the PTC inlet and outlet oil temperatures were computed. The result is a deviation < 4.25 % (rms) between measured to simulated values. Finally, in the third step, the C-TES model was validated as a stand-alone component. The deviation between measurement and simulated values is < 5 % compared to the design point