Abstract:
A method of improving the efficiency of a heat pump system comprising introducing into the system a carrier fluid with a polar compound comprising a corrosion inhibitor which is liquid under said systems operating conditions.

Description:
PARENT CASE TEXT  
       [0001]     The present application claims priority to U.S. Provisional Patent Application Ser. No. 60/484,338, filed in the United States Patent and Trademark Office on Jun. 30, 2003. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     Since the early 1970&#39;s there has been a constant effort to improve the energy efficiency of heating and cooling units which function on the heat pump principle. As is well known, heat pumps function by relying upon the energy absorbed or released as a compressible fluid undergoes either pressure increase in a compressor or pressure decrease across a valve or other orifice. Typically, these systems rely upon phase changes from the gas to liquid state as a result of changes in pressure to effectuate heat transport. Such heat pump units are utilized for large commercial installations either for refrigeration or freezing of perishable articles and the like as well as for climate control of large commercial buildings as well as individual dwellings. The energy efficiency of these units has been greatly increased through redesigned compressors, motors and other mechanical and design improvements. Improved methods for lubricating compressors have been developed so as to reduce the frictional energy that must be overcome in the compressor while new compressor designs have also been developed in an attempt to increase the energy efficiency of the systems. However, a need still exists for continued energy improvement in the field of heat pumps.  
         [0003]     It is an object of the present invention to improve the energy consumption in the field of heat pumps.  
         [0004]     Vapor compressors such as commercial heat pumps and the like typically utilize other components in addition to the basic components such as oil separators, suction-line, or liquid accumulators, liquid receivers, mufflers, recuperative heat exchangers, reversing valves, high pressure and low pressure safety switches, thermal overload protection, and filter-driers.  
         [0005]     A vapor compression heat pump utilizes a refrigerant evaporating at low pressure and low temperature to provide the cooling. This refrigerant vapor is then superheated slightly in the evaporator to avoid sending incompressible liquid to the compressor and compressed by the compressor to a higher pressure, thereby raising the condensation temperature so that the heat can be rejected to the environment as the refrigerant condenses to a liquid state. This liquid is then throttled in an expansion device to a two-phase mixture, which enters the evaporator to complete the process. In many cases, the compressor, which provides the compression of the refrigerant, must be lubricated to maximize compressor life and a lubricant compatible with the refrigerant and the materials of construction must be utilized. The proper lubricant to use for a particular type of refrigerant, compressor configuration, and temperature range is well known in the art. For example, in vapor compression system using HFC-134a refrigerant, it has been proposed to use tetraglyme by itself as the lubricant, but tests have demonstrated that it is not an acceptable lubricant. It is also well known that the lubricant used in the compressor becomes entrained in the refrigerant discharged from the compressor outlet and travels throughout the system. The refrigerant traveling throughout the system typically has an oil concentration of up to 5% by weight, the exact oil concentration being circulated being dependent on the compressor design, plumbing considerations, and the presence or absence of an oil separator, which is located directly downstream of the compressor outlet and returns the oil to the compressor.  
         [0006]     Numerous attempts have been made in the past to improve the performance characteristics of the vapor compression system. Each such attempt, however, introduces some additional complication or disadvantage into the system.  
         [0007]     Attempts have also been made to improve cooling performance via either additives or improved lubrication to reduce the friction loss in the compressor. For example, with regard to the former of the two approaches, U.S. Pat. No. 4,963,280 describes a composition for improving the energy efficiency of heat pumps by improving the heat transfer in the evaporator and condenser. A polar molecule, which is a liquid halogenated alpha-olefin or liquid halogenated paraffin is postulated to form a Van der Waals bond with the metal surface of the heat exchanger thereby assumedly reducing the thermal boundary layer. The polarity of the molecule is believed to result in the polar compound physically attaching itself to the metal walls of the heat pump system. The metal surfaces in the heat pump system are believed to contain a high electron charge such that the present polar molecule will orientate itself towards and form a Van der Waals bond with the metal surface. It is believed that when the polar compound binds to the metal wall that this results in a reduction in the boundary layer phenomenon, which is encountered in the transfer of heat from a fluid contained within a tube through the tube wall to the surrounding fluid. This boundary layer phenomenon reduces the heat transfer coefficient thereby decreasing efficiency. From tests conducted to date, it appears that the utilization of the polar compound significantly reduces the effect of this boundary layer phenomenon. Tests thus far have demonstrated not only lower energy consumption but also substantially increased heat transfer across the heat transfer surfaces. This improved heat transfer is demonstrated by an increase in the heat transfer coefficient for the system and by shorter system cycle times. As a result of the improved heat transfer, significantly reduced power consumption in the heat pump system has been observed. Further energy savings can be achieved by taking advantage of the increased heat transfer by reducing the overall size of the heat pump system for any given load thereby resulting in further energy efficiencies from the use of smaller compressors and the like.  
         [0008]     Attempts have also been made to incorporate the use of yellow metal deactivators, as is taught in patent number U.S. Pat. No. 6,276,147 and hereby incorporated as reference. Sgarbi, et al. Aug. 21, 2001.  
         [0009]     This approach attempts to boost performance through a significant improvement in the evaporative or condensation heat transfer, but has not proved to provide substantial yellow metal deactivation or inhibit rust and corrosion growth, which in turn forms sludge which results in costly maintenance and down time.  
         [0010]     With the addition of certain additives, some of which are soluble in the lubricants normally used in vapor-compressor system, that by adding this additive to the system, the additive would then travel throughout the system as part of, or mixed with, the lubricant that normally travels throughout the system. The additive can, but need not be, soluble in the lubricant and thus, like the lubricant, remains a liquid throughout the system. Therefore, regardless of how the additive is put into the system, or for example in the lubricant or elsewhere, it will become well mixed with the lubricant and travel with the lubricant as a liquid throughout the system.  
         [0011]     A performance-enhancing additive is introduced into a vapor compression system used in cooling and the like. Preferably the performance-enhancing additive is polar. The additive is selected from a class of compounds, preferably polar with a calcium sulfonate added to act as a yellow metal deactivator, or a rust growth inhibitor and added in a predetermined concentration measured relative to the mass of the system&#39;s lubricant. The additive can be soluble or non-soluble in the lubricant used in the system&#39;s compressor. It can be added anywhere in the system to provide lower thermodynamic load on the system compressor. Thermodynamics are the branch of physics that deals with the conversions from one to another of various forms of energy and how these affect temperature, pressure, volume, mechanical action and work in general.  
       BREIF SUMMARY OF THE INVENTION  
       [0012]     The present invention relates to the improvement in the energy efficiency and also reduces corrosion and sludge in heat pump systems including refrigeration units, heating and air conditioning systems, which pump heat from one location to another. The present invention also relates to a performance enhancing additive, and more particularly, to an additive for a basic vapor compression system such as cooling, air conditioning, heat pump and refrigerant systems, which dramatically improve the system&#39;s coefficient and performance and cooling capacity by lowering the thermodynamic load on the system compressor via lower pressure ratio and/or pressure difference, and which avoids the need for the more complicated approaches used in the past in enhancing cooling capacity and performance. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0013]     The preferred polar compounds are the liquid halogenated alpha-olefins and liquid halogenated paraffins; preferably the halogen is chlorine. With the most preferred group of polar compounds being liquid chlorinated .alpha-olefins. The liquid chlorinated .alpha-olefins and liquid chlorinated paraffin&#39;s must, remain liquid throughout the different operating phases of a heat pump system. While the molecular weight and degree of chlorination of these materials is not particularly critical, care should be taken not to use materials that contain a high wax content which may solidify in the expansion portion of the heat pump system. Such waxy materials can build up on valves and other aspects of the system causing malfunction or increase costly maintenance and down time. Furthermore, the presence of these solid components may impair the achievement of the desired energy improvement, thereby having a negative effect on the environment. Typically, both the liquid chlorinated .alpha-olefins and liquid chlorinated paraffins will contain from about 6 to 24 carbon atoms and from 1 to 10 or 12 chlorine atoms. The degree of chlorination and molecular weight determine the relative volatility and solidification points of the compounds. Of the chlorinated alpha-olefins particularly preferred is a product sold by Diamond Shamrock under the trade name Chlorowax-500AO that is a chlorinated alpha-olefin and has the formula of C.sub.12 H.sub.20 Cl.sub.6.  
         [0014]     Other chlorinated alpha-olefins and paraffins can be used with the degree of chlorination being chosen simply to render the compound sufficiently polar so as to have regions of high electron density while other regions have lower electron density. High and low electron densities are relative and the degree of difference between the two regions need not be great. The key concept is to have a charge distribution in the molecule.  
         [0015]     The preferred yellow metal deactivators or rust inhibitors used in the present invention are overbased calcium sulfonate containing calcium carbonate with a total base number:320 mgKOH/g, calcium content 12.5% by mass, sulfated ash content 42.5% by mass. Calcium sulfonate additives are alkaline in nature with an average pH of about 10. This pH range is too basic for active corrosion or rust to form and creates a passivating layer on metal surfaces. This alkaline or basic surface tends to neutralize any acids that penetrate the coating. This makes the additive ingredient calcium sufonate well suited to prevent corrosion caused by condensation. Calcium sulfonate forms a hydrophobic hydrocarbon chain structure that is positively charged and has a strong affinity for the negatively charged metal surface. This provides excellent adhesion to metal surfaces while preventing water from reaching the metal and thus denies one of the necessary ingredients for corrosion. Of the calcium sulfonates particularly preferred is a product sold by Lubrizol Corporation under the tradename Ircogel 906 and has the chemical name alkyl aryl. Calcium sulfonate is a viscose liquid in brownish color. In low concentrations, it has a red color, has a specific gravity of 1.018 (60 oC), viscosity of 1310.2 Cst (20 oC) &amp; 167.6 Cst (60 oC).  
         [0016]     It is surprising that calcium can act as a rust or corrosion inhibitor, as calcium is a soft silver-white element that is an alkaline earth metal constituting about three percent of the earth&#39;s crust.  
         [0017]     The preferred carrier for the polar compounds and calcium sulfonate is a refrigeration oil made by Sunoco and sold under the tradename Suniso 3GS. Sunisco 3GS is an oil expressly designed for use as refrigeration compressor lubricants, are miscible with HCFC and CFC refrigerants such as R-22, R-502 and R-12 while featuring excellent stability, thereby reducing maintenance and downtime and further creating a positive impact on the environment. The preferred refrigeration oil used in the present invention is refined from specially selected naphthenic crude oils by special method assuring excellent lubricity and make an excellent carrier and diluent for the above polar compounds and rust and corrosion inhibitor.  
         [0018]     The range percentages are as follows:  
                                   wt/%   Ingredient                   10.0-80.0%   Refrigeration Fluid 3GS       0.001-20.0%    Ircogel 906       0.01-65.0%   ChloroWax AO 500                  
 
         [0019]     The preferred formula is as follows:  
                                             wt/%   Ingredient                                58.27   Refrigeration Fluid 3GS       2.87   Ircogel 906       38.86   ChloroWax AO 500                  
 
 Add first two ingredients, mix on high speed for ten minutes. Add remaining ingredient and mix on high for another ten minutes. 
 
         [0021]     Performance summary: it has been noted that energy consumption and performance have increased from 1.0-22.0% using the present formula, which results in reduced negative impact on the environment as well as reducing down time and costly maintenance repairs.  
         [0022]     An example of the following test was performed:  
                                                 Main Chiller (350 Ton Centrifugal)                Before Treatment   After Treatment               (04/1 To 4/8)   (04/09 TO 04/16)   Variance               Chilled H2O   45. degree. F.   43. degree. F.   −2. degree. F.       Supply Temp.       Chilled H2O   54. degree. F.   50. degree. F.   −4. degree. F.       Return Temp       Condenser   88. degree. F.   82. degree. F.   −6. degree. F.       Supply Temp.       Condenser   94. degree. F.   90. degree. F.   −4. degree. F.       Return Temp.       Kilowatt Demand    280 kW     190 kW    −90 kW       KW/Ton (PLV)    .80 kW/ton     .54 kW/ton   −.26 kW/ton                   Run       Hours   168 hrs.   168 hrs.   0 hrs.       Temp.   69. degree. F.   64. degree. F.   −5. degree. F.       (Motor Casing)       Total kWh   47,040   31,920 kWh   −15,120                  
 
 Consumption 
 
         [0024]     The advantages regarding the test results as can be seen in the above table are notable in the sense that the variance of degrees are substantial when savings in energy consumption is a consideration. The decrease in kilowatt consumption is also significant, as it not only has a positive effect on the environment, but also reduces costly repairs and downtime.  
         [0025]     The oil migration into coils and evaporator units in an a/c and/or refrigeration system was found to be detrimental in heat transference. Oil absorbs energy. The layer of oil on the metal surface acts as an insulative blanket or layer that reduces the designed metal&#39;s (copper/aluminum) ability to transfer heat.  
         [0026]     The present invention is also chemically stable to resist chemical reaction with the refrigerant or other material normally present in the system. Thermally stable to eliminate excessive carbon deposits at compressor hot spots such as valves or discharge ports and has a low wax content to prevent separation of flocculent wax from the oil-refrigerant mixture at the low temperature points in the system. Flocculent wax is mass of solids that precipitate in a liquid solution and caused by a chemical reaction. The preferred refrigeration fluid also prevents separated oil from congealing in refrigeration lines, has high dielectric strength to insure good insulating properties. In hermetic units, the oil-refrigerant mixture serves as an insulator between the motor and the compressor body, while maintaining the proper viscosity even when diluted with refrigerant so as to insure high film strength at elevated operating temperatures and while providing good fluidity under coldest operating conditions, and prevents contamination, thereby preventing scarring of bearing surfaces, plugging of lines or oil ports and general deterioration. The preferred formula also inhibits rust and corrosion, thereby reducing sludge formation, reducing down time and costly maintenance, increasing energy efficiency and having a positive effect on the environment.