Stoves and furnaces – Solar heat collector – Having external damage preventer
Reexamination Certificate
2001-11-28
2004-02-10
Basichas, Alfred (Department: 3743)
Stoves and furnaces
Solar heat collector
Having external damage preventer
C126S572000, C126S589000, C126S599000, C126S600000, C126S683000, C126S684000, C060S641800
Reexamination Certificate
active
06688303
ABSTRACT:
1. FIELD OF THE INVENTION
The invention relates to a system and method for controlling a solar collector or solar concentrator. More specifically, the system and method relate to a controller system and associated software for accepting sensor inputs from sensors on the solar collector to determine the state of operation of an energy conversion device associated with the concentrator. In particular, the sensors provide information relative to the energy conversion device operating above a certain capacity, indicated, for example, by overheating, and the controller system issues commands to control the focusing of the solar collector, and executing instructions based on the energy conversion device condition to avoid operation above a desired capacity, while maintaining the energy conversion device online and operational.
2. BACKGROUND OF THE INVENTION
Solar collector or concentrator systems are used to collect solar energy from sunlight and convert it to a usable form of energy. The terms “solar collector,” “solar concentrator,” “collector,” “concentrator,” and “solar dish” or “dish” are used interchangeably herein to indicate the collector and concentrator portion of the solar collector, although, as would be understood by one of ordinary skill in the art, a solar collector or concentrator is not necessarily dish-like in shape.
One example of converting solar energy to usable energy is that solar energy may be stored in a battery for future use, or it may be used to generate power using a solid state device or an engine system. Such devices are referred to herein as a Power Conversion System (“PCS”). One such engine system commonly used in solar collector systems is a Stirling engine, which is a type of engine that derives mechanical power from the expansion of a confined gas at a high temperature. However, the system and method disclosed herein may be adapted for use with any PCS.
For example, other types of PCS's may include photovoltaic cells which convert light energy into electricity. For purposes of this description, all such types of PCS systems and devices are generally referred to herein as “energy conversion device(s).”
Solar collector systems typically include motion controlling systems to change the orientation of the collector. As the sun moves across the sky, the solar collector orientation must be changed accordingly to track the position of the sun by compensating for the earth's rotation. One complication arising from the use of solar collectors or concentrators is that high wind conditions may cause damage to solar collector systems because solar collectors are typically placed on a pedestal above the ground. Therefore, to avoid such damage, the solar collector is normally lowered or stowed in a safer orientation if high wind conditions exist.
The motors and drive systems used to control the orientation of a solar collector system may be controlled electronically by some combination of manual commands entered by a user. Alternatively, sensors may be placed to monitor various conditions of the solar collector, and a microprocessor may issue commands to change the orientation of the solar collector system based on the sensor inputs.
Current programming techniques used on such microprocessors are based on a hierarchical methodology. As used herein, the terms “program algorithm,” “program routine,” “program subroutine,” “algorithm,” “routine,” and “subroutine” are used interchangeably to refer to any block of code that may be logically grouped together and may or may not use the conventional subroutine interfaces as defined by typical programming languages. As would be understood by one of ordinary skill in the art, a program routine or subroutine is generally understood as a stylistic convention of programming, and thus different routines or subroutines may be written in multiple combinations and accomplish the same function. Thus, as used herein, a program algorithm, routine or subroutine encompasses any block of code logically grouped together regardless of whether conventional subroutine interfaces, as defined by typical programming languages, are used.
In a hierarchical program, the programming algorithm operates in a sequential manner, and the orientation of the solar collector is known to a system operating in accordance with the algorithm, based on previously issued commands. For example, the programming algorithm is initialized to certain starting parameters to indicate the starting orientation of the solar collector. If a user enters a command to place the solar collector into an operational state, the system implementing the programming algorithm issues instructions to the motors and drive systems to move a given direction in order to be placed in operational orientation. If the solar collector is moved again, for example, to track the sun, the information from the previously executed commands is used to determine what commands must be issued to re-orient the solar collector. By “state” or “collector state” is meant the combination of all the known status indicators of the collector, which may include positional orientation, temperature, wind conditions, etc.
If an error in the system occurs, it is difficult or impossible to issue new commands correctly. That is, if the program implementing the algorithm is unable to determine the correct orientation of the solar collector from its past history, it cannot accurately issue new commands or instructions. Error detection is also difficult in such a system. If the program implementing the algorithm has an error, it will continue to operate even though it may be issuing commands based on incorrect assumptions about the solar collector orientation. If such a system is turned off and restarted in mid-operation, the program routine does not have correct starting parameters, and therefore, is unable to issue correct control commands.
One particular type of solar collector system currently in use involves the use of a concentrator having stretched membrane mirror facets. Such systems have been installed and are known commercially by the name SunDish™. Such systems have has been operationally installed through the cooperation of The Salt River Project (SRP), Science Applications International Corporation (SAIC), STM Corporation and the U.S. Department of Energy. Further details about such a system are disclosed in a document entitled The Salt River Project SunDish™ dish-Stirling System, authored by Jessica Mayette (Salt River Project), Roger L. Davenport and Russell Forristall (SAIC).
Such a concentrator typically has 16 round, stretched membrane mirror facets. The stretched membrane mirror facets consist of a rolled steel ring with stainless steel membranes welded to the front and back surfaces of the ring.
Thin, typically 1-mm, low-iron glass mirrors, attached with adhesive to the front membrane, provide the reflective surface. The facets are focused by pulling a slight vacuum between the membranes using a blower system. Such a system allows fine-tune adjustment of the focal length during alignment of the system.
The use of such membranes, however, may give rise to complications in operation. More specifically, in the case of dish-engine systems where an energy conversion device such a Stirling engine is used, it is normally desirable to operate the engine near its peak power point to optimize efficiency. However, solar energy varies seasonally and over the course of the day. If the engine cannot accept the power available from the concentrator at any given time, due to optional focusing at high solar radiation levels, it will overheat.
One solution has been to off-track, i.e., no longer track the sun, with the dish, but this drops system output to zero, and may overheat other components that the beam tracks across. The other solution is to oversize the engine relative to the dish so that it never sees more power from the dish than it can handle. This is costly, and leads to lower system efficiency since the engine operates lower on its power curve most of the time.
Such overheating can also occur in
Davenport Roger L.
Smith David C.
Basichas Alfred
Kilpatrick & Stockton LLP
Science Applications International Corporation
LandOfFree
Method and system for controlling operation of an energy... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and system for controlling operation of an energy..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and system for controlling operation of an energy... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3290975