Author
Andreas Pfahl
Bio: Andreas Pfahl is an academic researcher from German Aerospace Center. The author has contributed to research in topics: Heliostat & Wind engineering. The author has an hindex of 12, co-authored 35 publications receiving 552 citations.
Papers
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TL;DR: Strong efforts are being made to drive heliostat cost down, with new approaches even target cost of 75$/m2 seem to be realistic.
108 citations
TL;DR: The case studies presented in this paper show that the new heliostat design can reduce the receiver spillage loss by 10-30%, and provide a much more uniform performance without large variations with time of day.
Abstract: The basic mathematics and structure of heliostat have remained unchanged for many decades. Following the challenge first made by Ries et al., the non-imaging focusing heliostat recently proposed by Chen et al. provides an alternative in the field of concentrated solar energy. This paper investigates the performance of a heliostat field composed of the newly proposed heliostats. In contrast to the dynamic curvature adjustment proposed in our previous work for a solar furnace, a fixed asymmetric curvature is used here with the spinning-elevation tracking method. This restriction is intended to equalize the manufacture cost of the new heliostat with that of traditional heliostats with azimuth-elevation tracking and spherical curvature. Fixing the curvature results in only partial aberration correction, compared to full correction using the dynamic adjustment of curvature. Nevertheless, the case studies presented in this paper show that the new heliostat design can reduce the receiver spillage loss by 10-30%, and provide a much more uniform performance without large variations with time of day.
83 citations
TL;DR: In this paper, the wind load coefficients for heliostats of aspect ratios between 0.5 and 3.0 were determined, and the effect of the aspect ratio on the wind loads on the structure of a solar tracker was investigated.
66 citations
TL;DR: In this paper, a survey of hitherto concepts for cost reduction of heliostats is given, which might serve as a base for the development of low cost heliastats that are needed to meet the current challenging cost objectives.
Abstract: A survey of hitherto concepts for cost reduction of heliostats is given. The survey might serve as a base for the development of low cost heliostats that are needed to meet the current challenging cost objectives. The concepts are related to the main heliostat subfunctions and to basic approaches for cost reduction found so far. Based on the main advantages and drawbacks of every concept, the most promising ones are indicated.
46 citations
TL;DR: In this paper, it is shown that the wind load coefficients on heliostats are not Reynolds number independent. But the effect of the inclination of the mirror plane in stow position, due to the deflection of the heliastat's structure at high Reynolds number, leads to increased wind loads and must be considered.
41 citations
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TL;DR: In this article, the authors reviewed the most important studies on the major components of central receiver solar thermal power plants including the heliostat field, the solar receiver and the power conversion system.
Abstract: The use of central receiver system (CRS) for electricity production promises to be one of the most viable options to replace fossil fuel power plants. Indeed, research and development activities on its basic subsystems have been booming rapidly since 1980s. This paper reviews the most important studies on the major components of central receiver solar thermal power plants including the heliostat field, the solar receiver and the power conversion system. After an overview of Concentrating Solar Power (CSP) technology, current status and applications of the CRSs are highlighted. Next, a detailed literature survey of existing design comprising optical, thermal and thermodynamic analysis, and techniques used to assess components have been arranged. This is followed by experimental investigations in which design concepts are established. The last section contains recent subsequent improvement of such key components as heliostat, receiver and hybrid solar gas turbine that are boosting in many R&D activities merging international collaboration during the past 30 years.
575 citations
TL;DR: A multitude of advancements have been developed during this period, as the topic of concentrated solar power is becoming more mainstream as mentioned in this paper, including reflector and collector design and materials, heat absorption and transport, power production and thermal storage.
477 citations
Patent•
12 Aug 2014TL;DR: In this paper, a ring-shaped user interface component is used to track a rotational input motion of a user, and a processing system is configured to identify a setpoint temperature value based on the tracked input motion, and an electronic display coupled to the processing system.
Abstract: A thermostat for controlling an HVAC system is described, the thermostat having a user interface that is visually pleasing, approachable, and easy to use while also providing ready access to, and intuitive navigation within, a menuing system capable of receiving a variety of different types of user settings and/or control parameters. For some embodiments, the thermostat comprises a housing, a ring-shaped user-interface component configured to track a rotational input motion of a user, a processing system configured to identify a setpoint temperature value based on the tracked rotational input motion, and an electronic display coupled to the processing system. An interactive thermostat menuing system is accessible to the user by an inward pressing of the ring-shaped user interface component. User navigation within the interactive thermostat menuing system is achievable by virtue of respective rotational input motions and inward pressings of the ring-shaped user interface component.
442 citations
01 Jan 2010
TL;DR: A multitude of advancements have been developed during this period, as the topic of concentrated solar power is becoming more mainstream as mentioned in this paper, including reflector and collector design and materials, heat absorption and transport, power production and thermal storage.
Abstract: This work focuses on innovation in CSP technologies over the last decade. A multitude of advancements has been developed during this period, as the topic of concentrated solar power is becoming more mainstream. Improvements have been made in reflector and collector design and materials, heat absorption and transport, power production and thermal storage. Many applications that can be integrated with CSP regimes to conserve (and sometimes produce) electricity have been suggested and implemented, keeping in mind the environmental benefits granted by limited fossil fuel usage.
433 citations
TL;DR: Techniques for efficient solar collection, thermal storage, and power generation at >700 °C and barriers on the way to the high-temperature CSP are summarized.
213 citations