Air curtain control system and method

Abstract

An air curtain control system for a solar thermal receiver comprising: at least one air jet ( 505 ) arranged to produce a continuous planar air curtain ( 507 ) over at least a portion of a receiver aperture 509 of a solar thermal receiver, an air flow control device ( 517 ) for controlling a speed of air flow out of the air jet ( 505 ), at least one angular control device ( 503 ) for controlling an angle of the air curtain ( 507 ) relative to the receiver aperture 509 , and a system controller ( 501 ) arranged to control the air flow control device ( 517 ) and angular control device ( 503 ) to isolate the receiver aperture ( 509 ) from ambient elements external to the receiver aperture ( 509 ).

1 . An air curtain control system for a solar thermal receiver comprising:
 at least one air jet arranged to produce an air curtain over at least a portion of a receiver aperture of a solar thermal receiver,   an air flow control device for controlling a speed of air flow out of the air jet, at least one angular control device for controlling an angle of the air curtain relative to the receiver aperture, and   a system controller arranged to control the air flow control device to isolate the receiver aperture from ambient elements external to the receiver aperture.   
     
     
         2 . The air curtain control system of  claim 1 , wherein the system controller is arranged to control the angular control device to isolate the receiver aperture from ambient elements external to the receiver aperture. 
     
     
         3 . The air curtain control system of  claim 2 , wherein the system controller is arranged to control the air flow control device and angular control device by controlling one or more of the speed of air flow and the angle of the air curtain based on a predetermined algorithm. 
     
     
         4 . The air curtain control system of  claim 3 , wherein the predetermined algorithm is configured based on one or more of a temperature of a receiver cavity of the solar thermal receiver, an inclination of the receiver aperture, pressure in, around or near the receiver cavity computational fluid dynamics models, measured performance characteristics and fundamental flow physics. 
     
     
         5 . The air curtain control system of  claim 1 , wherein the system controller is arranged to control the air flow control device and angular control device based on one or more input signals, wherein the one or more input signals are selected from an inclination of the receiver aperture, temperature(s) in a receiver cavity of the solar thermal receiver, the angle of the air curtain relative to the receiver aperture, the speed of the air flow out of the air jet, ambient wind speed, ambient wind direction, ambient wind temperature and sun position. 
     
     
         6 . The air curtain control system of  claim 1 , wherein the system controller further comprises a memory with a look up table, wherein the look up table is used by the system controller to adjust one or more of the speed of air flow and the angle of the air curtain based on an inclination of the receiver aperture. 
     
     
         7 . The air curtain control system of  claim 1  wherein the at least one air jet is arranged to direct the air curtain from a position located vertically above the receiver aperture. 
     
     
         8 . The air curtain control system of  claim 1  wherein the system controller is arranged to operate in a first mode where the at least one air jet is arranged to direct the air curtain over less than a full portion of the receiver aperture. 
     
     
         9 . The air curtain control system of  claim 8  wherein the system controller is arranged to operate in the first mode and the angular control device is controlled by the system controller so the source angle of the air curtain relative to the receiver aperture is up to 20 degrees from a plane lying across the receiver aperture. 
     
     
         10 . The air curtain control system of  claim 8  wherein the system controller is arranged to operate in the first mode and the angular control device is controlled by the system controller so the angle of the air curtain relative to the receiver aperture is between 10 degrees and 20 degrees from a plane lying across the receiver aperture. 
     
     
         11 . The air curtain control system of  claim 9  or  10  wherein the angle of the air curtain relative to the receiver aperture is either directed away from the solar thermal receiver or towards the solar thermal receiver. 
     
     
         12 . The air curtain control system of  claim 1  wherein the system controller is arranged to operate in a second mode where the at least one air jet is arranged to direct the air curtain over a full portion of the receiver aperture. 
     
     
         13 . The air curtain control system of  claim 12  wherein the system controller is arranged to operate in the second mode and the angular control device is controlled by the system controller so the angle of the air curtain relative to the receiver aperture is between 0 degrees and 20 degrees from a plane lying across the receiver aperture and directed away from the solar thermal receiver. 
     
     
         14 . The air curtain control system of  claim 13 , wherein the angular control device is controlled by the system controller so that the angle of the air curtain relative to the receiver aperture is between 5 degrees and 15 degrees from a plane lying across the receiver aperture and directed away from the solar thermal receiver. 
     
     
         15 . The air curtain control system of  claim 1  further comprising an air extraction device for extracting air out of the solar thermal receiver. 
     
     
         16 . The air curtain control system of  claim 1  further comprising an air injection device for injecting air into the solar thermal receiver. 
     
     
         17 . The air curtain control system of  claim 1  further comprising an air extraction device for extracting air out of the solar thermal receiver and an air injection device for injecting air into the solar thermal receiver. 
     
     
         18 . The air curtain control system of  claim 1  further comprising an air flow generator for generating airflow out of the air jet. 
     
     
         19 . The air curtain control system of  claim 1  wherein the system controller is arranged to control the air flow control device so that the speed of air flow out of the air jet is between 1 and 27 metres per second. 
     
     
         20 . The air curtain control system of  claim 1  comprising a single air jet arranged to produce the continuous planar air curtain over at least a portion of the receiver aperture. 
     
     
         21 . The air curtain control system of  claim 20  wherein the air jet is comprised of a single rectilinear nozzle. 
     
     
         22 . The air curtain control system of  claim 1  comprising a plurality of air jets arranged to produce the continuous planar air curtain over at least a portion of the receiver aperture. 
     
     
         23 . The air curtain control system of  claim 22  wherein the air jets are comprised of a series of rectilinear nozzles arranged linearly. 
     
     
         24 . The air curtain control system of  claim 22  wherein the air jets are comprised of a series of round nozzles arranged linearly. 
     
     
         25 . The air curtain control system of  claim 22  wherein the air jets are comprised of a series of round nozzles arranged in a zig-zag manner. 
     
     
         26 . The air curtain control system of  claim 1 , wherein the one or more air jets have nozzles with a width between 5 mm and 100 mm. 
     
     
         27 . The air curtain control system of  claim 1  further comprising a solar thermal receiver comprising the receiver aperture. 
     
     
         28 . An air curtain control method for a solar thermal receiver comprising the steps of:
 producing an air curtain from at least one air jet over at least a portion of a receiver aperture of a solar thermal receiver,   controlling a speed of air flow out of the air jet,   controlling an angle of the at least one air jet relative to the receiver aperture, wherein the air flow speed and angle of the air curtain are controlled to isolate the receiver aperture from ambient elements external to the receiver aperture.   
     
     
         29 . The air curtain control method of  claim 28  further comprising the step of controlling one or more of the speed of air flow and the angle of the air curtain based on a predetermined algorithm. 
     
     
         30 . The air curtain control method of  claim 29 , wherein the predetermined algorithm is configured based on one or more of a temperature(s) in a receiver cavity of the solar thermal receiver, an inclination of the receiver aperture, computational fluid dynamics models, measured performance characteristics and fundamental flow physics. 
     
     
         31 . The air curtain control method of  claim 28 , wherein the air flow speed and angle of the air curtain are controlled based on one or more input signals, wherein the one or more input signals are selected from an inclination of the receiver aperture, a temperature(s) in a receiver cavity of the solar thermal receiver, pressure in, around or near the receiver cavity the angle of the air curtain relative to the receiver aperture, the speed of the air flow out of the air jet, ambient wind speed, ambient wind direction, ambient wind temperature and sun position. 
     
     
         32 . The air curtain control method of  claim 28 , further comprising the step of using a look up table to adjust one or more of the speed of air flow and the angle of the air curtain based on an inclination of the receiver aperture. 
     
     
         33 . The air curtain control method of  claim 28  further comprising the step of directing the air curtain from a position located vertically above the receiver aperture. 
     
     
         34 . The air curtain control method of  claim 28  further comprising the step of operating in a first mode where the at least one air jet is arranged to direct the air curtain over less than a full portion of the receiver aperture. 
     
     
         35 . The air curtain control method of  claim 34  wherein the source angle of the air curtain relative to the receiver aperture is up to 20 degrees from a plane lying across the receiver aperture. 
     
     
         36 . The air curtain control method of  claim 35  wherein the source angle of the air curtain relative to the receiver aperture is between 10 degrees and 20 degrees from a plane lying across the receiver aperture. 
     
     
         37 . The air curtain control method of  claim 35  or  36  wherein the source angle of the air curtain relative to the receiver aperture is either directed away from the solar thermal receiver or towards the solar thermal receiver. 
     
     
         38 . The air curtain control method of  claim 28  further comprising the step of operating in a second mode where the at least one air jet is arranged to direct the air curtain over a full portion of the receiver aperture. 
     
     
         39 . The air curtain control method of  claim 38  wherein the source angle of the air curtain relative to the receiver aperture is between 0 degrees and 20 degrees from a plane lying across the receiver aperture and directed away from the solar thermal receiver. 
     
     
         40 . The air curtain control method of  claim 39 , wherein the source angle of the air curtain relative to the receiver aperture is between 5 degrees and 15 degrees from a plane lying across the receiver aperture and directed away from the solar thermal receiver. 
     
     
         41 . The air curtain control method of  claim 28  further comprising the step of extracting air out of the solar thermal receiver. 
     
     
         42 . The air curtain control method of  claim 28  further comprising the step of injecting air into the solar thermal receiver. 
     
     
         43 . The air curtain control method of  claim 28  further comprising the steps of extracting air out of the solar thermal receiver and injecting air into the solar thermal receiver. 
     
     
         44 . The air curtain control method of  claim 28  further comprising the step of controlling the speed of air flow out of the air jet to between 1 and 27 metres per second. 
     
     
         45 . The air curtain control method of  claim 28  further comprising the step of producing the continuous planar air curtain over at least a portion of the receiver aperture. 
     
     
         46 . A solar thermal receiver comprising at least one air jet arranged to produce an air curtain over at least a portion of a receiver aperture of a solar thermal receiver, an air extraction device for extracting air out of the receiver aperture and an air injection device for injecting air into the receiver aperture.