A thermostatic expansion valve txv see figure 1 is a refrigeration and air conditioning throttling device that controls the amount of refrigerant liquid injected into a systems evaporatorbased on the evaporator outlet temperature and pressurecalled the superheat. A thermal expansion valve often abbreviated as tev, txv, readers digest august 20 usa pdf or tx valve is a component in. The valves control the injection of liquid refrigerant into evaporators and protect the compressor motor against liquid refrigerant. It is based on the second law of thermodynamics that the heat can made to flow from cold body to a hot body with the help of external source. Cross reference the pressuretemperature chart to see what the temperature should be for that pressure. Lpa involves the addition of a pump to provide stable pressure to the expansion valve.
Valve expansion valve liquid refrigerant from condenser return gas to compressor 70% liquid 30% vapor mix 1. An electrically driven device which regulates the flow of volatile refrigerant into an evaporator of a refrigeration system. In the below example we will compare a thermostatic expansion valve with an electric expansion valve. Freon mo99 refrigerant, invented and patented by chemours, combines r22 pressureenthalpy characteristics with mineral oil compatibility in a unique hfc refrigerant that can be used to replace r22 over a wide range of evaporator temperatures. References are stated in the text in the format x, where x refers to the number in. The oev valve family offers 5 port sizes to cover a wide range of capacities. Th movement cooling by the removal of heat the movement of heat from a. The control objective is defined as improving the transient behavior of the vapor compression cycle for the refrigeration system operating around an evaporator. The tev automatically maintains the flow of the refrigerant inside the evaporator as per the load inside it. The solenoid expansion valves in series 2028 illustrated in this chapter can be.
Pressure regulator sometimes called a backpressure valve maintains the higher evaporating temperature in the first evaporator. The items described in this document and other documents and descriptions. Dynamic modelling of charges for thermostatic expansion valves. Sporlan selection program for hvacr applications is new. It regulates the refrigerant flow into the evaporator by modulating the opening.
This entire line is supplied with stainless steel stems for maximum corrosion resistance and back seating capability. Expansion valve for ac browse air conditioning txv. Explanation of the operation of a thermostatic expansion valve. Firstly, it is important to understand the main principles and operations within the refrigeration production cycle. Make sure the if electrical power will be connected prior to evacuation and charging of system, unplug piping is correctly sized and properly routed.
The liquid then moves to the expansion valve under high pressure. All expansion valves illustrated in this technical handbook. Tev enables safe running of the compressor without flooding and also helps the refrigeration plant run as per the optimum capacity. Thermostatic expansion valves regulate the injection of liguid refrigerant into evaporators. Temperature drops to saturated suction temperature c. In the danfoss range of thermostatic expansion valves you can find the product to match your needs, no matter the cooling application or refrigerant used.
We will also detail the differences between a thermostatic expansion. Inside thermal expansion valves the engineering mindset. Pressure drop in distributors and evaporator is assumed to be zero. Differences between a thermostatic expansion vs valve and. Differences between a thermostatic expansion valve and an electronic expansion valve in this article we will explain in a simplified way what is the role of the expansion valve iin the refrigeration production cycle. The pressure regulator may be simply modeled as an expansion valve. The pressure drop causes the evaporating temperature of the refrigerant to fall below that of the evaporator. Modelling thermostatic expansion valves article pdf available in international journal of refrigeration 381. Technical specifications from an expansion valve manufacturer were used to select the 30 psi setpoint for highest average expansion valve capacity during all outdoor air temperature and food case load conditions. Expansion valve head pressure control valve condenser liquid line sight glass drier.
Adjusting expansion valves for correct superheat can be frustrating by the book it seems simple enough. Definitions solenoid valves are found in many applications and are commonly used in refrigeration and air conditioning systems. Solenoid valves and their importance in refrigeration systems. We will also detail the differences between a thermostatic expansion valve and an electronic expansion valve. An expansion valve is a valve used for different purposes. Refrigeration fundamentals 2175 west park place blvd. Capacity rating of thermostatic expansion valves asercom. Injection is controlled by the refrigerant superheat. Expansion valves on medium temp systems normally do not have any frost or ice accumulation. A solenoid valveis an electromechanical valve frequently used to control the flow of liquid or gas. Electronic expansion valves reduce the significant energy. Expansion valve for ac and refrigeration browse txv. A txv is a mechanical device which controls the refrigerant mass flow by sensing pressure and temperature. The mass flow through the valve depends on refrigerant type, opening degree of the valve and the pressure drop across the valve.
Expansion valves are devices used to control the refrigerant flow in a refrigeration system. The fixed area restrictor expansion device is simply a precisely formed restriction through which liquid refrigerant flows. Different types of valves with pdf file engineering. Expansion valve for ac browse air conditioning txv valves. Therefore the valves are especially suitable for liquid injection in dry evaporators where the superheat at the evaporator outlet is. Liquid refrigerant passes through expansion valve a. Technical brochure thermostatic expansion valves, tub and tuc series introduction the tu series of thermostatic expansion valves is speci.
Expansion devices can be divided into four general categories. To cool the refrigerant down it is passed through the expansion valve. Having achieved the goal of fiftyfive years working in the refrigeration and air conditioning industry, castels range of. Manual valve expansion illustrates the main means by which the refrigerant is measured through all adjustable devices of the account. The co2 transcritical booster refrigeration system is comprised of following subsystems subsystems, or modules. Ahri standard 751 si2016 1 performance rating of thermostatic refrigerant expansion valves section 1. Beijer ref lithuania jsc represents manufacturers like danfoss we are the only one authorized danfoss representative in refrigeration and air conditioning area, bitzer, carel, armacell, frascold, carrier, refco and many others factories and suppliers we offer a wide range of over 25,000 items of refrigeration equipment products.
Refrigeration 9 of up to 25% for larger plant 300kw and a payback of three to five years. Refrigeration system discharge pressure operated at 125 pounds per square inch gage. The speed of the refrigerant flow through the valve is determined by three things. With danfoss thermostatic expansion valves, you can expect precise operation and long service life of your refrigeration system. The refrigeration cycle collects this heat by sending the refrigerant at a low temperature and pressure into the evaporator within that room. To cool a room down, the heat within that room must be collected and dumped somewhere else. Expansion valve steam engine the bestknown of these was the meyer expansion valve, the invention of jeanjacques meyer. Refrigeration systems expansion valves expansion valves the expansion valve is the regulator through which the refrigerant passes from the high pressure side of the system to the low pressure side. Whats inside a thermal expansion valve and how the thermostatic expansion valve or txv works in a hvac refrigeration system. A controlling device which regulates the flow of volatile refrigerant into an evaporator of a refrigeration system and which is actuated by changes in evaporator pressure and superheat of the refrigerant gas leaving the evaporator. Refrigeration and air conditioning questions answers. A valve used to expand a gas, for thermodynamic cooling purposes in either.
For use on refrigeration andor air conditioning systems only. Pdf impact of txv and compressor in the stability of a highend. Just read the pressure and temperature of the suction line as it leaves the evaporator. Differences between a thermostatic expansion valve and an. They help to facilitate the change of higher pressure of liquid refrigerant in the condensing unit to lower pressure gas refrigerant in the evaporator. The complete industrial refrigeration line of hand shutoff and expansion valves with bolton bonnets are designed and built to maintain reliability both in their seating and back seating functions. Canada with file mh50005, in compliance with american standard ul 429 and. Fitters notes chapter 1 thermostatic expansion valves, spanish, castilian. Equipment used include compressor, condenser, steam container, rotameter, sightglass, filter drier, thermal expantion valve, capillary expansion valve, evaporator, highlow pressurestat, and manometer.
Expansion valves industrial refrigeration product group catalogue. The thermostatic expansion valve allows you to keep a constant superheat or. Expansion valve for refrigeration and light commercial air conditioning applications the sporlan type oev valves are the latest line of unipolar electric expansion valves that will help achieve the optimal balance between performance and cost. After making your selections, you can create a pdf report rpt field containing all of your inputs, valve selection, and calculated values or export the values in an excel file. The ex4ex8 are stepper motor driven valves that are optimized for the control of liquid or gaseous mass flow in refrigeration systems multifunction capability as expansion valve, hot gas bypass, suction gas throttling, head pressure, liquid line actuator and other applications systems. In vapour compression cycle, the condition of refrigerant is very wet vapour a after passing through the condenser b before passing through the condenser c after passing through the expansion or.
In this article we will explain in a simplified way what is the role of the expansion valve iin the refrigeration production cycle. Condensing pressure is allowed to float with ambient temperatures. A thermostatic expansion valve txv see figure 1 is a refrigeration and air conditioning throttling device that controls the amount of refrigerant liquid injected. The purpose of this standard is to establish for thermostatic refrigerant expansion valves. This results in a loss of efficiency but is easier to control than the previous configuration. Compressor basic refrigeration cycle evaporator condenser receiver expansion device. Copeland scroll compressors for refrigeration applications. A system that is low on refrigerant will have ice or frost on the valve. In this refrigeration experiment the material used is a chemical refrigerant22 chclf2 or chlorodifluoromethane.