The throttling effect is to reduce the inlet pressure by a constant enthalpy process (represented by horizontal line AB). The result is a loss in entropy and also a slight fall in temperature with some reduction in the available heat drop. This accounts for a small loss in efficiency.
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What is a throttle in thermodynamics?
Throttling device is the generic name of any device or process that simply dissipates pressure energy by irreversibly converting it into thermal energy. Unlike nozzles and diffusers, throttling devices provide no form of useful energy recovery.
What is throttle process?
Throttling process is a thermodynamic process which is used to reduce or decrease the pressure of a fluid. In this process a liquid having high pressure is converted into low pressure fluid.
What is throttling of a gas?
Gas throttling is reduction of pressure in a gas flow forced through a throttle โ local hydrodynamic resistance point (orifice choke, valve, tap, check), accompanied by temperature change. Gas throttling is used for liquefying and deep refrigeration of gases.
What is throttling process with example?
An example of a throttling process is an ideal gas flowing through a valve in mid position. From experience we can observe that: Pin > Pout, velin < velout (where P = pressure and vel = velocity). These observations confirm the theory that hin = hout.
How does throttling affect flow?
A: Throttling valves are a type of valve that can be used to start, stop and regulate the flow of fluid through a rotodynamic pump. When the flow of a pump is regulated using a throttling valve, the system curve is changed. The operating point moves to the left on the Pump curve when the flow is decreased.
Why does throttling increase entropy?
Because of the viscous heat generation in the throttling operation, the temperature change is small, and so the decrease in pressure (increase in volume) will result in an increase in entropy.
Why is throttling irreversible?
During the throttling process, no work is done by or on the system (dW = 0), and usually, there is no heat transfer (adiabatic) from or into the system (dQ = 0). On the other, the throttling process cannot be isentropic. It is a fundamentally irreversible process.
Does throttling reduce temperature?
In the throttling process the down stream pressure is always less than the upstream pressure . Therefore, whenever a real gas is subjected to throttling, the temperature of the gas decreases if the initial state lies in the region to the left of the isenthalpic curve.
How does throttling affect pressure?
The pressure drop in a throttling device is caused by the increase in velocity. The velocity is increased due to the decrease in area of the device that the fluid is flowing into and then out of (e.g. throttling valve, porous plug, capillary tube).
Why throttling process is adiabatic?
Since generally, throttling occurs in a small area, it may be considered as an adiabatic process (as the area available for heat transfer is negligibly small) (ฮดQ = 0) also since no external work is done (W = 0).
What are throttling losses?
The point at which the intake valves close is selected in a way that appears to reduce an engine’s displacement. Engine power output is prevented from falling by opening the throttle, ultimately diminishing throttling losses.
Is throttling isothermal?
In throttling process enthalpy remains constant, work done is zero. For ideal gas throttling process is isothermal and for real gases due to throttling the temperature may increase decrease or remain constant.
What is throttling in pumps?
Control by throttling is used to influence the flow rate in a pump system by varying system resistance. It is also the simplest way to shift the operating point of a centrifugal pump because it uses existing valves fitted inside, upstream, or downstream of the system.
Is temperature constant in throttling?
In other words, the gas passes through the porous plug in such a manner that its enthalpy remains constant. . Thus, the temperature of an ideal gas does not change in a throttling process.
Is throttling reversible?
Though throttling is an expansion process, it is fundamentally different from expansion taking place in a turbine. The expansion of a fluid in a turbine yields useful work output and can approach a reversible process (e.g. isentropic process), whereas expansion by throttling is highly irreversible.
Does internal energy change in throttling process?
In general, the change of internal energy is equal to heat added to the gas minus work done by the gas. During a throttling process, no heat is added and no work is done. So the internal energy of the gas remains the same.
What is flow throttling?
Flow which is forced to pass through a restricted area, where the velocity must increase.
Which valve is used for throttling?
The globe valve is primarily used as a throttling valve. This belongs to the linear motion valve family. The globe disk moves up or down in relation to the stationary ring seat. Its disk or plug controls the amount of media that can pass through.
Is a ball valve a throttling valve?
BALL VALVES Many people use them successfully for throttling clear water. Ball valves have low pressure drops, open and close quickly, are simple, and are trouble free. With the development of Teflon seals, ball valves have grown in popularity. Opening or closin a ball valve too quickly can cause fluid hammer.
What is entropy a function of?
Entropy is a function of the state of a thermodynamic system. It is a size-extensive quantity, invariably denoted by S, with dimension energy divided by absolute temperature (SI unit: joule/K). Entropy has no analogous mechanical meaningโunlike volume, a similar size-extensive state parameter.
Why throttling is not used in gas refrigeration system?
Detailed Solution. In gas refrigeration cycle air is used as refrigerant. During throttling the temperature of air will not decrease so we use an expander engine in place of throttle valve.
How can throttling be used for production of cooling?
Throttle valve reduces the pressure of high pressure liquid refrigerant to ensure the pressure difference between condenser and evaporator and make the liquid refrigerant in the evaporator evaporate and absorb the heat under low pressure, and finally achieve the purpose of cooling.
Which of the following is true for throttling process?
Explanation: When a fluid flows through a constricted passage, like a partially open valve, an orifice, or a porous plug, there is an appreciable drop in pressure and the flow is said to be throttled. Throttling is done in an insulated pipe with a partially open valve. i.e. enthalpy remains constant.
What is throttling in Mobile?
In simple terms, app throttling means to deliberately reduce the performance of a particular app. The aim of the throttling performance of apps on a smartphone is to boost the gaming performance and battery life.