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Refrigeration plantRelated Patent Categories: Refrigeration, Automatic Control, Refrigeration Producer, Of Or By Evaporation Zone, Of Expansion Valve Or Variable Restrictor, By Condition At Low Side, At Or Beyond Evaporator Outlet, I.e., SuperheatRefrigeration plant description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20050274133, Refrigeration plant. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority from European Patent Application No. 04425426.6 filed Jun. 10, 2004. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates the field of the refrigeration plants or systems, with particular--but not exclusive--reference to those of middle-great dimensions. [0004] More specifically, it concerns substantially a refrigeration plant having a flow regulation valve without metering orifice of limitation of flow. [0005] 2. Description of the Related Art [0006] Currently, several typologies of refrigeration plants are known, wherein expansion valves provided with metering orifice are employed. [0007] The invention refers to a solenoid valve without orifice which is periodically energized (opened) and de-energized (closed) by a control system that, in response to some parameters of the refrigeration plant (e.g. overheating), varies the ratio between the energizing time (opening) and the de-energizing time (closing) of the solenoid valve during each period of operation of the valve so that to regulate the flow of refrigerant that goes through the valve itself. [0008] Typically, a refrigeration plant includes a compressor, a condensing coil and a evaporating coil. Refrigerant vapor is compressed to high pressure by the compressor and supplied to the condenser where the high pressure refrigerant vapor is condensed to a high pressure liquid. An expansion valve is provided between the condenser and the evaporator so that the liquid refrigerant from the condenser can be adiabatically expanded before entering in the evaporator. In the latter, the low pressure refrigerant absorbs heat from the surrounding environment and it is transformed, at least partially, in a vapor which returns to the inlet of the compressor through a suction line. In many conventional refrigeration systems, the expansion valve is a so-called thermostatic expansion valve. The common thermostatic expansion valve, as for instance the known "Danfoss TE2" model, has an expansion port therein with a metering orifice and a valve member to regulate the flow of refrigerant through the expansion port. A spring biases the valve member toward its closing position, and it is provided a diaphragm actuator having a side of the diaphragm exposed to the pressure of the suction gas while the other side is connected, through a capillary pipe, to a thermostatic bulb which exchanges heat with the refrigerant vapor (also called "suction gas") exhausted by the evaporator. The bulb, which is loaded with a suitable volatile fluid (e.g. a refrigerant), exerts a pressure force on the valve member on the diaphragm actuator opposing the force of the spring and the pressure of the suction gas. When the thermostatic bulb detects an increase in the suction gas temperature with respect to its pressure, the clean pressure force exerted on the diaphragm actuator is correspondingly increased, thereby obtaining to increase the opening of the valve so as to allow to a greater quantity of refrigerant to flow through the evaporator, resulting in a drop in temperature of the suction gas. Following the detection of a diminution in the suction gas temperature by the thermostatic bulb, the latter decreases the pressure force exerted on the diaphragm actuator and thereby allows the spring to close at least partially the valve, reducing the flow of refrigerant in the evaporator and, in turn, increasing the temperature of the suction gas. In this way, the expansion valve regulates the overheating at the evaporator outlet, the overheating being defined as the difference between the temperature of the refrigerant vapor and the temperature of a saturated vapor of the same refrigerant to the same pressure. [0009] The expansion valves of known type have generally the following limitations: [0010] A. To get the maximum efficiency from the evaporator, an overheating near to zero at the evaporator outlet would be desirable, but such known valves, with values of the overheating smaller than about 4.div.6.degree. C., are normally not able to carry out suitable regulations, causing a decrease of efficiency of the evaporator between 5 to 10%. [0011] B. When the flow of refrigerant through the valve of expansion is smaller than about 50% of the valve full opening flow capacity, the valve starts to swing between excessive opening and excessive closing, leading to a reduced efficiency of the refrigeration system and to dangerous refrigerant liquid feeding to the compressor inlet. Usually, in order to avoid these swings, the maximum valve capacity is reduced but in this way the refrigeration system cannot operate at its maximum capacity and efficiency in every operating condition. [0012] C. In the currently known refrigeration systems, with air cooled condenser, during the winter operation the pressure at the condenser drops, so reducing the valve flow capacity below acceptable limits. The common solution is to limit the air flow to the condenser by switching off some of the condenser fans so as to ensure that the refrigerant pressure is not less than 8.div.12 bars. It should be noted that at a lower condenser pressure, the refrigeration system would have a higher capacity and a lower power consumption, but this condition is not allowed by the thermostatic valve intrinsic limitation. [0013] D. The gaseous phase of the refrigerant entering into the expansion valve limits the flow through the metering orifice which is normally calculated for refrigerant completely in liquid phase. To avoid such limitation, the connection to the valve is generously oversized and the quantity of refrigerant in the system is greater than the amount that would be otherwise necessary. Often a liquid receiver is also installed between the condenser and the expansion valve: the additional refrigerant in the receiver compensates possible variations in the operating conditions of the refrigeration system. The providing of the compensating receiver leads to a further increase of the total quantity of refrigerant. Furthermore, the presence of a receiver having a capacity greater than a certain value imposes the observance of onerous and restrictive regulations, particularly of the European Union (such as the 97/23/CE, also known as PED). [0014] E. During the winter operation, the value of the pressure at the condenser usually results lower than the values of the pressure of the other periods of the year and in order to avoid that refrigerant in gaseous phase being supplied to the expansion valve, a quantity of refrigerant greater than that really necessary has to be provided in the plant. Thus, the pressure at the condenser should be maintained over to a certain value otherwise it must be furnished a greater quantity of refrigerant. [0015] Some of said drawbacks have been overcame by adopting thermostatic expansion valves electronically controlled. [0016] The U.S. Pat. No. 4,112,703, discloses an electromechanical valve working also as expansion device in the refrigeration circuit, wherein the refrigerant expands while it flows through the valve, going out of the valve in the form of a two-phase mixture of liquid and gas in which the preponderant phase is the liquid phase. [0017] The valve is used for furnishing a varying orifice correspondingly to the applied control. [0018] In the U.S. Pat. No. 4,459,819 it is disclosed a simple solenoid valve provided with a metering orifice intended to limit the flow of the refrigerant. In this case, the solenoid is periodically activated and de-activated to control the flow of refrigerant in response to the overheating of the refrigerant at the evaporator outlet. [0019] The expansion valve known with the commercial name of "Danfoss AKV" is conceptually similar to the U.S. Pat. No. 4,459,819: in substance, it concerns a solenoid valve incorporating a metering orifice which is activated every six seconds and subsequently deactivated after a suitable time calculated by a proportional, differential and integral electronic controller. [0020] The patent DE3419666 discloses the same simple solenoid incorporating a metering orifice, used as expansion valve for air conditioning for generic use and for heat pumps. [0021] In all these valves the refrigerant liquid reaches the valve inlet and therefore it expands while it is flowing through of it. Thus, these electronically controlled valves replicate the function of the traditional expansion valve, improving the precision of the regulation of the overheating and widening the range of flow capacity with respect to that of the traditional expansion valves. These electronically controlled valves overcome the limitations previously listed as A, B and C, but don't overcome the limitations listed as D and E. [0022] To such intention, it should be noted that since common refrigerants of the HFCs type cause greenhouse effect, it would be extremely advantageous to reduce the quantity of refrigerant required for the good operation of a refrigeration plant. Furthermore, the use of a reduced quantity of refrigerant would also allow the elimination of the liquid receiver, whose presence often involves, as already said, heavy burdens under the regulations point of view for the certification and the management of the plant itself. Continue reading about Refrigeration plant... Full patent description for Refrigeration plant Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Refrigeration plant patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Refrigeration plant or other areas of interest. ### Previous Patent Application: Pressure control valve and vapor-compression refrigerant cycle system using the same Next Patent Application: Air conditioner Industry Class: Refrigeration ### FreshPatents.com Support Thank you for viewing the Refrigeration plant patent info. IP-related news and info Results in 0.30971 seconds Other interesting Feshpatents.com categories: Qualcomm , Schering-Plough , Schlumberger , Seagate , Siemens , Texas Instruments , 174 |
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