Ice removal from hvacr surfaces

Abstract

A vapor compression heat transfer system includes an evaporator assembly, an ice-prone surface, and an ultrasonic energy source. The ultrasonic energy source when energized vibrating the ice-prone surface at a frequency of from 30 kHz to 60 kHz. The ultrasonic energy source can be a piezoelectric transducer. The piezoelectric transducer can be operated in an ice sensing mode and a deicing mode and can also verify the removal of ice. A method of conducting one of heating, ventilation, air conditioning and refrigeration (HVACR) is also disclosed.

We claim: 
     
         1 . A vapor compression heat transfer system, comprising an evaporator assembly and an ice-prone surface, and an ultrasonic energy source, the ultrasonic energy source when energized vibrating the ice-prone surface at a frequency of from 30 kHz to 60 KHz. 
     
     
         2 . The vapor compression heat transfer system of  claim 1 , wherein the vapor compression system comprises at least one selected from the group consisting of an ice maker, heat pump, air conditioner, a refrigerator, and a freezer. 
     
     
         3 . The vapor compression heat transfer system of  claim 1 , wherein the ultrasonic energy source comprises a transducer. 
     
     
         4 . The vapor compression heat transfer system of  claim 3 , wherein the transducer is a piezoelectric transducer. 
     
     
         5 . The vapor compression and heat transfer system of  claim 4 , wherein at least two piezoelectric transducers are connected to the ice-prone surface, and each transducer is spaced from 12 in. to 18 in. from an adjacent transducer. 
     
     
         6 . The vapor compression heat transfer system of  claim 1 , wherein the evaporator assembly comprises an evaporator tube having an ice-prone surface, and the ultrasonic energy source vibrates the ice-prone surface and the evaporator tube. 
     
     
         7 . The vapor compression heat transfer system of  claim 6 , wherein the evaporator assembly comprises an evaporator fin thermally and mechanically coupled with the outer surface of the evaporator tube, at least one of the evaporator tube and the evaporator fin comprising an ice-prone surface, such that vibration of one of the evaporator tube and the evaporator fin by the ultrasonic energy source will vibrate the ice-prone surface. 
     
     
         8 . The vapor compression heat transfer system of  claim 7 , wherein the evaporator tube and/or the evaporator fin comprises at least one selected from the group consisting of Cu, Al, Fe, and alloys thereof. 
     
     
         9 . The vapor compression heat transfer system of  claim 1 , further comprising a layer of icephobic material coated on the ice-prone surface, wherein the icephobic material will reduce ice formation on the ice-prone surface during operation of the evaporator and reduce adhesion of the formed ice to the ice-prone surface. 
     
     
         10 . The vapor compression heat transfer system of  claim 9 , wherein the icephobic material comprises polymeric low interfacial toughness (LIT) material. 
     
     
         11 . The vapor compression heat transfer system of  claim 10 , wherein the LIT material is at least one selected from the group consisting of polydimethylsiloxane (PDMS) and polytetrafluoroethylene (PTFE). 
     
     
         12 . The vapor compression system of  claim 1 , wherein the evaporator assembly comprises supporting structure for the evaporator, and the ultrasonic energy device is mechanically connected to the supporting structure such that the ultrasonic energy source will vibrate the supporting structure and the vibration will be transmitted through the supporting structure to the evaporator and the ice-prone surface. 
     
     
         13 . The vapor compression heat transfer system of  claim 1 , further comprising controller circuitry communicatively coupled with the ultrasonic energy source and configured to instruct the ultrasonic energy source to vibrate the ice-prone surface to cause removal of ice from the ice-prone surface. 
     
     
         14 . The vapor compression heat transfer system of  claim 13 , further comprising an ice detector for detecting the presence of ice on the ice-prone surface, the ice detector being connected to the controller circuitry to operate the ultrasonic energy source when a threshold amount of ice is detected by the ice detector on the ice-prone surface. 
     
     
         15 . The vapor compression heat transfer system of  claim 14 , wherein the ice detector comprises at least one selected from the group consisting of resistive sensor, photoelectric sensors, fiber optic sensors, and capacitive sensors. 
     
     
         16 . The vapor compression heat transfer system of  claim 15 , wherein the ice detector comprises an impedance analyzer, the impedance analyzer measuring the impedance of the ice-prone surface and producing an impedance signal relating to the impedance of the ice-prone surface to the controller circuitry, the controller circuitry determining from the impedance signal the resonant frequency of the ice-prone surface and comparing the resonant frequency to a set point resonant frequency for the ice-prone surface to determine the presence of ice on the ice-prone surface. 
     
     
         17 . The vapor compression heat transfer system of  claim 14 , wherein the ultrasonic energy source is operable as an ice detector in an ice-detecting mode, in conjunction with the controller. 
     
     
         18 . The vapor compression heat transfer system of  claim 17 , wherein the ultrasonic energy source is operable in the ice-detecting mode over a range of 0.05 W/in 2 -0.1 W/in 2 , and in an ice-removal mode over a range of 0.5 W/in 2 -1.5 W/in 2 . 
     
     
         19 . The vapor compression heat transfer system of  claim 14 , wherein the controller circuitry comprises a function generator configured to energize the ultrasonic energy device according to predetermined functions. 
     
     
         20 . A low temperature chamber having walls and a ceiling comprising an ice-prone surface, the chamber comprising one or more ultrasonic energy sources disposed on one or more of the walls or the ceiling, the ultrasonic energy source when energized vibrating the ice-prone surface at a frequency of from 30 kHz to 60 KHz. 
     
     
         21 . The low temperature chamber of  claim 20 , wherein the chamber is at least one selected from the group consisting of cold storage, walk-in freezer, reach-in display case, frozen fry dispenser, walk-in cooler, and refrigerated transportation container. 
     
     
         22 . The low temperature chamber of  claim 20 , further comprising an evaporator attached to the low temperature chamber. 
     
     
         23 . The low temperature chamber of  claim 20 , further comprising a layer of icephobic material coated on the ice-prone surface, wherein the icephobic material will reduce ice formation on the ice-prone surface while the temperature in the chamber is below the dew point temperature and reduce adhesion of formed ice to the ice-prone surface. 
     
     
         24 . The low temperature chamber of  claim 23 , wherein the icephobic material comprises a low interfacial toughness (LIT) material, wherein the LIT material is at least one selected from the group consisting of polydimethylsiloxane (PDMS) and polytetrafluoroethylene (PTFE). 
     
     
         25 . A method of conducting one of heating, ventilation, air conditioning and refrigeration (HVACR), wherein the HVACR system comprises an evaporator assembly and an ice-prone surface, the method comprising the steps of:
 providing an ultrasonic energy source; and,   operating the ultrasonic energy source to vibrate the ice-prone surface at a frequency of from 30 KHz to 60 KHz.   
     
     
         26 . The method of  claim 25 , further comprising the step of using an ice detector to determine whether ice formed on the ice-prone surface has exceeded a predetermined upper threshold, and selectively instruct the ultrasonic energy source to vibrate the ice-prone surface in response to the determination; and, using the ice detector to determine whether the formed ice has fallen below a predetermined lower threshold, and selectively turn off the ultrasonic energy source to cease vibration of the ice-prone surface in response to the determination. 
     
     
         27 . The method of  claim 25 , further comprising the step of instructing the ultrasonic energy source to vibrate the ice-prone surface in accordance with a predetermined schedule. 
     
     
         28 . The method of  claim 25  wherein the HVACR system comprises at least one selected from the group consisting of an ice maker, heat pump, air conditioner, a refrigerator, and a freezer. 
     
     
         29 . The method of  claim 25 , wherein the power per unit area produced by the ultrasonic energy source is from 0.5 W/in 2  to 1.5 W/in 2 . 
     
     
         30 . An evaporator assembly for a heating, ventilation, air conditioning and refrigeration (HVACR) apparatus, the evaporator assembly comprising an evaporator and an ice-prone surface, and an ultrasonic energy source, the ultrasonic energy source when energized vibrating the evaporator at a frequency of from 30 KHz to 60 KHz.