Abstract:
A system for purifying a fluid uses ultra violet (UV) light to inactivate micro-organisms present in the fluid. The system has an arrangement of UV light emitters on perforated plates. The fluid, while passing through perforations in the perforated plates, is exposed to the UV light emitted by the UV light emitters. Micro-organisms present in the fluid pass very close to the UV light emitters. The UV light absorbed by the micro-organisms causes genetic damage and inactivation. The system has feedback units providing feedback about the physical properties of the fluid to a power unit supplying power to the UV light emitters. The power unit varies the amount of power supplied to the UV light emitters, based on the feedback.

Description:
FIELD OF INVENTION  
       [0001]     This invention relates to a system for purification of fluids using Ultra Violet (UV) light, and in particular, to a system for purification of fluids using UV light emitters mounted on perforated plates.  
       BACKGROUND  
       [0002]     Some fluids like water and air, used in day-to-day life, can be contaminated with micro-organisms. The presence of micro-organisms in fluids, for example, in water used for drinking, may have a detrimental effect on the health of the consumer. Hence, the micro-organisms present in fluids should be inactivated before the fluids are used for consumption.  
         [0003]     One way of purifying fluids is by using ultra violet (UV) light emitted by an UV light emitter. UV light, in the range of 260-to-280 nm, is absorbed by the DNA, RNA and protein in micro-organisms, for example bacteria and virus, causing genetic damage and inactivation.  
         [0004]     There exist systems which use UV light for the purification of fluids. However, the known systems for purification of fluids using the UV light require a good transmittance of the fluids. Transmittance, in terms of fluid treatment with UV light, is the ability of the UV light to travel through a fluid, or more specifically, the fraction of a given amount of the UV light that can be measured through the fluid at a given point. Currently, commercially available UV fluid purification systems require that at least 75% of transmitted UV light reaches a distance of 1 cm from the UV light emitters. As the turbidity of the fluids increases, their transmittance decreases. Low transmittance of the fluids decreases the amount of exposure of the micro-organisms to UV light, thereby, reducing the effectiveness of the known systems in inactivating these micro-organisms.  
         [0005]     What is needed is a system for the purification of fluids that can work efficiently even for a fluid with a low transmittance.  
       SUMMARY  
       [0006]     The present invention provides a system that is used for the purification of fluids, using UV light emitters mounted on perforated plates.  
         [0007]     In one embodiment, perforated plates with UV light emitters mounted on them are housed inside a chamber. A fluid that is to be purified passes through perforations in the perforated plates. The UV light emitters are mounted very close to the perforations. The dimensions of the perforations in the perforated plates are such that micro-organisms present in the fluid come in close proximity to the UV light emitted by the UV light emitters. In case of high turbidity of the fluid, which results in low transmittance of the UV light, the close exposure of the micro-organisms to the UV light emitters ensures that the micro-organisms absorb a sufficient amount of UV light required for their inactivation.  
         [0008]     In another embodiment, the invention also employs a feedback-based power control unit and feedback units to control power supplied to the UV light emitters. The feedback units provide data about the physical properties of the fluid to the feedback-based power control unit. Based on the received data, for example flow-rate of the fluid and intensity of the UV light inside the fluid, the feedback-based power control unit varies the amount of power supplied to the UV light emitters.  
         [0009]     In yet another embodiment, the invention employs UV light-reflecting screens on walls of the chamber, to increase density of the UV light inside it. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]      FIG. 1  is a diagram depicting a system for the purification of a fluid, in accordance with an embodiment of the invention.  
         [0011]      FIG. 2  is a front view of a perforated plate with UV light emitters mounted on its surface, in accordance with an embodiment of the invention.  
         [0012]      FIG. 3  is a block diagram illustrating interactions among a feedback-based power control unit, feedback units, and UV light emitters, in accordance with an embodiment of the invention.  
         [0013]      FIG. 4  is a diagram depicting a system with only one perforated plate for the purification of a fluid, in accordance with an embodiment of the invention.  
         [0014]      FIG. 5  is a diagram depicting a system with four perforated plates for the purification of a fluid, in accordance with an embodiment of the invention. 
     
    
       [0015]     Elements in the various figures designated by the same numerals may be similar or identical to one other.  
       DETAILED DESCRIPTION  
       [0016]      FIG. 1  is a diagram depicting a system  100  for the purification of a fluid, in accordance with an embodiment of the invention. Two perforated plates  104  are housed inside chamber  102 . Perforated plates  104  have UV light emitters mounted on their surface. In an embodiment of the invention, perforated plates  104  may be modified to fit into any other container. For example, perforated plates  104  may be modified to fit into a cylindrical pipe carrying water. Chamber  102  has an inlet  106  and an outlet  108 . The fluid enters chamber  102  through inlet  106  and passes through perforations in perforated plates  104 . The fluid may be air, water or any other liquid or gas. The UV light emitters may be UV Light Emitting Diodes (LEDs), such as UVTOP LEDs, manufactured by Sensor Electronic Technology Inc.  
         [0017]     The micro-organisms present in the fluid, while passing through the perforations in perforated plates  104 , are exposed to UV light emitted by the UV light emitters. The UV light is absorbed by the DNA, RNA and protein in the micro-organisms. The UV light causes genetic disorder and inactivation of the micro-organisms. Perforated plates  104  expose both front and rear of the micro-organisms to the UV light.  
         [0018]     In an embodiment of the invention, a feedback-based power control unit and feedback units are employed to control amount of power supplied to the UV light emitters (This is not shown in  FIG. 1 ). The feedback units provide data about the physical properties of the fluid to the feedback-based power control unit. Depending on the received data, the feedback-based power control unit varies the amount of power supplied to the UV light emitters.  
         [0019]     System  100  also includes UV-reflecting screens  110 . UV-reflecting screens  110  cover walls of chamber  102 . Any UV light incident on UV reflecting screens  110  is reflected back to chamber  102 , increasing density of the UV light inside chamber  102 . In an embodiment of the invention, UV-reflecting screens  110  are made of aluminium.  
         [0020]      FIG. 2  is a front view of a perforated plate  104  with UV light emitters  202  mounted on its surface, in accordance with an embodiment of the invention. Perforated plate  104  has UV light emitters  202  arranged in an array on its surface. Perforated plate  104  has perforations  204  to allow the fluid to pass through. In an embodiment of the invention, perforated plate  104  may be a Printed Circuit Board (PCB). In another embodiment of the invention, perforated plate  104  is a Metal Core Printed Circuit Board (MCPCB). The metal core of the MCPCB makes it a good conductor of heat. The metal core effectively transfers heat generated by UV light emitters  202  to a heat sink. Effective transfer of heat to the heat sink keeps UV light emitters  202  in their ideal operating temperature range, thereby increasing efficiency of system  100 . Low temperatures are required for efficient operation of the LEDs, preferably in the range of 20° C. to 60° C.  
         [0021]     In an embodiment of the invention, perforations  204  are square in shape. Perforations  204  allow the fluid to pass through and expose the micro-organisms present in the fluid to the UV light. Dimensions of perforations  204  determine proximity of the micro-organisms to UV light emitters  202 . The dimensions of perforations  204  are decided based on UV light emission capacity of UV light emitters  202 . The dimensions of perforations  204  are large for high power UV light emitters  202 , whereas the dimensions of perforations  204  are small for low power UV light emitters  202 .  
         [0022]     In an embodiment of the invention, distance, hereinafter referred to as pitch, between two consecutive UV light emitters  202  is 10 millimeters (mm). A small pitch, 10 mm, of the UV light emitters  202  implies closer proximity of the micro-organisms to the UV light. The pitch of UV light emitters  202  depends on the UV light emission capacity of UV light emitters  202 . The pitch is large for high power UV light emitters  202 , and it is small for low power UV light emitters  202 . A pitch of 10 mm ensures that at any point of time any micro-organism is not more than 5 mm away from UV light emitters  202 . This ensures that a sufficient amount of the UV light is absorbed by the micro-organisms. High density of UV light emitters  202  on perforated plate  104  further increases exposure of the micro-organisms to the UV light.  
         [0023]     In an embodiment of the invention, insulation windows are used to insulate UV light emitters  202  from the fluid. The insulation windows prevent short circuiting of electrical contacts by the fluid and protect the structure from contamination. The insulation windows facilitate transmission of the UV light to the fluid. In an embodiment of the invention, an insulation layer covers perforated plate  104 . The insulation window and the insulation layer may be made from one of quartz, silicon dioxide, and glass.  
         [0024]      FIG. 3  is a block diagram illustrating interactions among a feedback-based power control unit  302 , feedback units  304   a  and  304   b,  and UV light emitters  202 , in accordance with an embodiment of the invention. Feedback-based power control unit  302  is employed to control amount of power supplied to UV light emitters  202 . Feedback based power control unit  302  takes input from feedback units  304   a  and  304   b,  and accordingly varies the amount of power supplied to UV light emitters  202 . Feedback units  304   a  and  304   b  provide fluid-flow data and UV light intensity data to feedback based power control unit  302 .  
         [0025]     In an embodiment of the invention, feedback unit  304   a  is a fluid-flow sensor placed on perforated plate  104 . Feedback unit  304   a  measures flow-rate inside chamber  102 , and provides fluid-flow data to feedback-based power control unit  302 . For example, when there is no flow of the fluid, feedback-based power control unit  302  switches off UV light emitters  202 . As the fluid starts flowing, feedback unit  304   a  informs feedback-based power control unit  302  about the flow and feedback-based power control unit  302  switches on UV light emitters  202 . Depending on flow-rate of the fluid, feedback-based power control unit  302  adjusts amount of power supplied to UV light emitters  202 . If the flow-rate of the fluid increases, the time spent by the fluid inside chamber  102  decreases. This, in turn, decreases amount of the UV light absorbed by the micro-organisms. Therefore, as the flow-rate of the fluid increases, the intensity of the UV light generated by UV light emitters  202  is increased by supplying more power to UV light emitters  202 . Similarly, if the flow-rate of the fluid decreases, the time spent by the fluid inside chamber  102  increases; and consequently, the micro-organisms absorb more than required amount of the UV light. Therefore, as the flow-rate decreases, the intensity of the UV light generated by UV light emitters  202  is decreased by supplying less power to UV light emitters  202 , thereby saving electric power.  
         [0026]     In an embodiment of the invention, feedback unit  304   a  accumulates information pertaining to the flow of the fluid by measuring change in temperature of perforated plate  104 . The UV light emitters  202  heat up perforated plate  104 . In the absence of any flow in the fluid, the temperature of perforated plate  104  remains constant. As the fluid starts flowing, the temperature of perforated plate  104  drops. Based on drop in the temperature of the fluid, feedback unit  304   a  measures the flow of the fluid and provides the fluid-flow data to feedback-based power control unit  302 .  
         [0027]     In another embodiment of the invention, feedback unit  304   a  calculates the fluid-flow data by measuring strain in perforated plate  104 . The flow of the fluid develops different strains in different parts of perforated plate  104 . Feedback unit  304   a  measures the strains and uses their values to calculate the fluid-flow data.  
         [0028]     In an embodiment of the invention, feedback unit  304   b  is an UV light sensor inside chamber  102 . Feedback unit  304   b  measures UV light intensity at its location and provides the UV light intensity data to feedback-based power control unit  302 . The UV light output of UV light emitters  202  may vary over time. Feedback unit  304   b,  by measuring the UV light intensity, ensures that system  100  is working and meeting desired performance requirements. The UV light intensity is different in different parts of chamber  102  because turbidity of the fluid varies in different parts of chamber  102 . Feedback unit  304   b  keeps a track of the turbidity of the fluid by measuring the UV light intensity inside chamber  102 . Feedback-based power control unit  302  adjusts the power supplied to UV light emitters  202  based on the UV light intensity data provided by feedback unit  304   b.  Thereby, the intensity of UV light generated by UV light emitters  202  is adjusted according to the intensity of the UV light in different parts of chamber  102 .  
         [0029]      FIG. 4  is a diagram depicting a system  400  with only one perforated plate for the purification of a fluid, in accordance with an embodiment of the invention. A chamber  402  houses a perforated plate  404  with UV light emitters mounted on it. Chamber  402  has an inlet  406  and an outlet  408 . The fluid enters from inlet  406 , passes through perforations on perforated plate  404 , and comes out of chamber  402  from outlet  408 . The UV light emitted by the UV light emitters mounted on perforated plate  404  disinfects micro-organisms present in the fluid. UV light-reflecting screens  410  reflect any UV light incident on them back to chamber  402 .  
         [0030]      FIG. 5  is a diagram depicting a system  500  with four perforated plates for purification of a fluid, in accordance with an embodiment of the invention. A chamber  502  houses four perforated plates  504  with UV light emitters mounted on them. Chamber  502  has an inlet  506  and an outlet  508 . The fluid enters from inlet  506 , passes through perforations on perforated plates  504 , and comes out of chamber  502  from outlet  508 . The UV light emitted by the UV light emitters mounted on perforated plates  504  disinfects micro-organisms present in the fluid. UV light-reflecting screens  510  reflect any UV light incident on them back to chamber  502 .  
         [0031]     Advantages of this system used for purification of fluids using UV light emitters include:  
         [0032]     Greater exposure of the micro-organisms to the UV light emitters as both front and rear of the micro-organisms are exposed uniformly to the UV light.  
         [0033]     Efficient use of electric power is achieved by varying the power supplied to the UV light emitters, based on input supplied by the feedback units to the feedback-based power control unit.  
         [0034]     Longer life of the UV LEDs used for emission of the UV light.  
         [0035]     Use of the fluid to be purified as a cooling agent for the UV light emitters. The fluid keeps the UV light emitters in an ideal operating temperature range.  
         [0036]     Efficient transmission of heat from the UV light emitters to a heat sink by the metal core of the MCPCB. The metal core keeps the UV light emitters in an ideal operating temperature range.  
         [0037]     Availability of information about flow of the fluid inside the chamber.  
         [0038]     Availability of information about the intensity of UV light inside the chamber.  
         [0039]     While particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from this invention in its broader aspects and, therefore, the appended claims are to encompass within their scope all such changes and modifications as fall within the true spirit and scope of this invention.