Answer / palash

I dont get the first question?
Whatever I am trying to give some answers according to the
questions.

First question is "Is expansion valve a throttle valve".
The answer is, it is not necessary always.Because there are
several types of expansion valve like

1. Hand (manual) expansion valves
2. Capillary Tubes
3. Orifice
4. Constant pressure or Automatic Expansion Valve (AEV)
5. Thermostatic Expansion Valve (TEV)
6. Float type Expansion Valve
7. Electronic Expansion Valve


Coming to the Second question,capillary tube is a
long ,narrow tube of constant diameter.the main purpose of
it is to reduce pressure from condensor to evapourator to
continue the flow.In capillary tube because of following
two reasons pressure is dropped down.

1)The refrigerant has to overcome the frictional resistance
offered by tube walls. This leads to some pressure drop

2)the average density difference in the tube (mixture of
liquid and vapour refrigerant) makes some velocity
increases which in term drops the pressure.




Coming to third question :throttling valve is not a kind
of pressure reducing valve,rather its a flow control valve
to control the flow of the system as per required for the
system
,whereas capillary tube is fixed opening type tube to
reduce the liquid refrigerant pressure to the evapourator
pressure.

sorry for the lengthy answer. :(

Answer / g.s sharma

Expansion valve may not be necessary that it can be a
throttling valve because in throttling valve flow is
restricted therefore velocity increases and pressure
decreases which reduces the out let pressure hence
temperature get reduced

Answer / ibrahim_mahmoud

Thank u very much for this illustrated answer.

i know that throttling is a process where enthalpy is
constant and the pressure only decreases . Is the
tempertature is constant too during this throttling process?
and plz what r the applications for throttling and throttle
valve in our life?
thx

Answer / seshasai

As pressure changes during throttling, temperature also changes. A throttle is used in S.I engine to control charge intake(which is connected to accelerator in our bikes ).

Answer / vikash bharti

Dear Ibrahim your concept is very right. Temperature is not constant after the process of throttling because after the process of expansion pressure decreases and we know that if pressure will decrease temperature will also decrease.

can anyone plz send me question papers of DMRC for the post of junior engineer.(MECHANICAL) OR STATION CONTROLLER I wud b highly obliged. plz mail me at manpreet.sodhi08@gmail.com MANPREET SINGH

0 Answers   DMRC,

---

WHAT HAPPENS TO THE VOLUME OF SOLIDS BY INCREASES TEMPERATURE OF THAT SOLID

1 Answers   L&T, Titan,

---

If a dimension is given as SC parameter, is supplier allowed to use full range of tolerance specified in drawing without proving capability?

0 Answers  

---

tell me about a time when u had to many things to do and u were required opinion prioritized your talks.

0 Answers  

---

HRSG

1 Answers   L&T,

---

---

what is mist lubrication?give examples where it is used?

1 Answers  

---

What is seamless pipe

4 Answers   Armco,

---

What are the advantages of white metal?

0 Answers   Reliance, RRB,

---

When effect of variations in specific heats is considered then how do maximum temperature and pressure vary compared to air standard cycle ?

0 Answers  

---

how to calculate bearing number?

4 Answers   NRB Bearings, NTN, SKF,

---

What is the principle of mechanical refrigeration ?

0 Answers  

---

If any machinery or trnsmission needs periodic and regular lubrication what is the best method to give?

0 Answers   Essar,

---