August 13th, 2020
Although breweries show a high heat demand at a low temperature level, it is relatively difficult to estimate in the first instance, if a solar heating system can be reasonable integrated into the existing processes. This is based on the diversity and complexity of the brewing process, as explained before. The basis for this decision is the detailed knowledge of the water – and energy balance of the overall production process. Some breweries don’t have any noteworthy hot water consumers beside the brewhouse, which can even lead to a surplus of hot water gained by heat recovery. In this case, the hot water is drained to the sewer and a non-concentrating solar heating system cannot be installed reasonably...Read More
The evaluation of the hygrothermal behavior of the chamber was carried out together with agronomic trials during winter. The heated beds and the pipes in contact with the grafted area contributed to raise the temperature inside the chamber. Fig. 3 shows three consecutive days measuring: it can be observed how the chamber reaches maximum temperatures (RT ins.) of 30°C and minimum values of 10°C, while the temperature outside (RT out.) was between 22°C and 6°C. Inside temperatures were maintained within the recommended limits. The three days had similar radiation levels with 730W/m2 at the most. The relative humidity during the first and third day was observed to be similar comparing the inside (RH. ins.) and outside (RH...Read More
The validation of the models is necessary to ensure that the calculated results are valid. Furthermore it is to proof what differences consist due to the assumptions made in the models.
The different components were validated mainly with calculation results of other software. The comparisons showed good agreement of the new models with the references for steady state simulation. The validation of the receiver model has been done with calculation results for one day from the DLR TRNSYS simulation model. The comparison (see Fig. 3) showed a difference in the absolute values but it could be shown that the model has the same behaviour as can be seen by the calculation of the power that reaches the boiler.
Fig. 3: Comparison results for the power Prec leaving the receiver
After the cons...Read More
Every kind of preheating has a negative effect on the total efficiency factor of the boiler or the power plant respectively. This is especially evident with condensing boiler technology because return-flow temperatures increased by solar energy reduce or block condensing boiler technology. However, also with every other back-up heating the total efficiency factor is decreased by preheating processes. The causes are e. g. higher standstill and operating losses as well as higher demand for pump energy and storage tanks.
4. Summarization, Conclusions
Tube collectors in general and especially CPC vacuum tube collectors with water as heat transfer medium have proved to have potential to simplify and improve solar-thermal systems so that flat plate collectors can be called outdated...Read More
Data gathered in the framework of the IEA Task 33/IV include comprehensive information about the geographical distribution of the solar thermal plants, the industrial sectors addressed, the specific processes, the process temperatures, the solar thermal collectors technologies, the capacity installed, the type of back-up systems and some economics. This survey include the majority of the worldwide built examples with few exceptions such as China and Japan. At the present time data collection comprises 19 countries. Plants in operation in Austria, Greece, Spain, Germany, Italy and the USA represent about 75% of the total installed capacity reported.
Currently about 90 operating solar thermal plants for process heat are reported worldwide, with a total capacity of about 25 MWth (35,00...Read More
In order to describe the woodchip drying curves and study how the drying factors affect, a series of tests were conducted at different temperatures and velocities.
Drying is the process of removal water from a product. As a thermal process, the performance of any dryer mainly depends on the construction, design parameters as well as the operating conditions: flow rate and heat input . During the tests, the weight of the sample, flow rate and psychrometric parameters: temperature and humidity were measured periodically using the appropriate instrumentation.
Sets of tests were undertaken at different temperatures, between 10°C and 50°C, for different drying velocities. The experimental drying velocities tested on the tray (area 0,25 m2) were up to 0...Read More
J. Koschikowski*, M. Wieghaus*, M. Rommel*,
Vicente Subiela Ortin**, Baltasar Penate Suarez**, Juana Rosa Betancort Rodriguez**
* Fraunhofer Institute for Solar Energy Systems ISE
Heidenhofstr.2,79110 Freiburg, Germany
email ioako@ise. fhg. de
** INSTITUTO TECNOLOGICO DE CANARIAS, S. A.
Playa de Pozo Izquierdo, s/n
35119 – Santa Lucia, Las Palmas
Tel: +34 928 727511 Fax: +34 928 727517
email: baltasarp@itccanarias. org
In many places world wide drinkable water is already a scarce good and its lack will rise dramatically in the future. Missing energy sources and no grid connections complicates the use of standard desalination techniques in these places...Read More
Rolf Meissner*, Stefan Abrecht
Paradigma Energie – und Umwelttechnik GmbH & Co. KG, department large-scale thermal-solar systems,
Ettlinger Str. 30, 76307 Karlsbad, Germany
Corresponding author: r. meissner@paradigma. de
The results of nearly 20 years of Paradigma research, development as well as the practical experience with more than 30.000 already realized solar systems according to the AquaSystem principle give enough evidence that CPC-ETC technology with pure water as heat transfer fluid is probably the most promising way to realize large-scale solar-thermal systems (LSS) and demanding solar-thermal systems at all. High temperature collectors increase the efficiency factor, allow an all-season application and are the key for effective heat storage.
Keywords: process heat, CPC...Read More