Why throttling process refrigeration

The constant-restriction type device is the capillary tube which is merely a long tube with narrow diameter bore. Additional Information. Start Learning English Hindi. This question was previously asked in. Evaporator Discharge valve Capillary tube Expansion valve.

Start Now. Explanation: An expansion device is essentially a restriction offering resistance to flow so that the pressure drops, resulting in a throttling process.

The thermodynamic function of expanding the liquid refrigerant from the condenser pressure to the evaporator pressure. There are two important functions performed by the throttling devices or the expansion valves as mentioned below:. The pressure of the refrigerant has to be reduced so that it can vaporize at the required temperature in the evaporator. The small opening or the orifice in the throttling valve reduces the pressure of the refrigerant to the level such that vaporization of the refrigerant occurs.

The refrigerant leaving the throttling valve enters the evaporator at low pressure, low temperature and partially liquid and vapor state. When there is more refrigeration load that means the quantity of the substance stored in the freezer is more and it is at higher temperature, more amount of heat is to be removed from it.

In such cases the throttling devise allows increased flow of the refrigerant through it. When the refrigeration load is less that means the quantity of the substance is less and it is at lower temperature, less amount of heat is to be removed from it. Assume the process is adiabatic and no work is done by the system.

See also: Steam Tables. Since it is an isenthalpic process, we know the enthalpy for point T. From steam tables we have to find the vapor quality using the same equation and solving the equation for vapor quality, x:.

In this case of the throttling process 1. Thermodynamic Processes. Search Search. In fact, the throttling process is one of isenthalpic processes. Nuclear and Reactor Physics: J. Lamarsh, Introduction to Nuclear Reactor Theory, 2nd ed. Lamarsh, A. Baratta, Introduction to Nuclear Engineering, 3d ed.

Particularly, the Throttling Process effect increases with the valve lift. Finally, the work has shown that all experimental data can be correlated by a single curve if an opportune dimensionless plot is adopted. Recent interest in natural refrigerants has created a new impetus for studies of CO2 as a working fluid in vapour compression systems for refrigeration and air conditioning.

Two major drawbacks to its use are the very high pressure differences required across the compressor and the large efficiency losses associated with the Throttling Process in the refrigeration cycle. It is shown how these disadvantages can be minimised by the use of a screw machine both to compress the gas and use the expansion Process to recover power. Both these functions can be performed simultaneously, using only one pair of rotors, in a configuration that partially balances out the forces induced by the pressure difference and hence, reduces the bearing loads to an acceptable level.

A further feature is the use of rotors, which seal on both contacting surfaces so that the same profile may be used for the expander and the compressor sections. This enables the rotors performing both these functions to be machined or ground in the same cutting operation and then separated by machining a parting slot in them. Computational Continuum Mechanics comprising both, fluid flow and structural analysis is used in this paper for the investigation of fluid-solid interaction in such machines.

Two major drawbacks to its use are the very high pressure differences required across the compressor and the large efficiency losses associated with the Throttling Process. To overcome the throttle losses, a number of proposals have been made for various types of positive displacement machine, mainly of the vane type, which combine compression with some recovery of work from the expansion Process.

However, how well they operate with high pressure differences across the vanes has not been confirmed. For many years, the authors have been investigating the use of twin screw machines to fulfil both the expansion and compression Process es when using more conventional halocarbon refrigerants. These have many potential advantages over other types of positive displacement machine. Unfortunately, when applied to CO2 the huge bearing forces associated with the pressure distribution within them have hitherto made them appear to be unsuitable.