Cold water machine expansion pneumatic valve installation and matching

expansion pneumatic valve mechanism as a cold water cooling system of big four large parts the throttle device a, cold water machine, cold water machine application expansion pneumatic valve appropriate choice and normal installation directly influence the refrigerating capacity of the screw chillers and the stable operation of the refrigeration system. A, matching

according to R, Q, t, tk, liquid pipeline and pneumatic valve resistance loss, steps:
to determine the expansion pressure difference at the ends of the pneumatic valve;
to determine the form of a pneumatic valve;
choose pneumatic valve type and specification.
and determine the differential pressure at the ends of the pneumatic valve:
Δ P = PK - ΣΔPi- Po( KPa
type: PK, condensing pressure, KPa, Σ Δ Pi for Δ P + P + P + Δ Δ Δ P ( Δ P for liquid pipeline resistance losses; Δ P for elbow, such as pieces of pneumatic valve resistance losses; Δ P for rising liquid tube pressure loss, Δ P = rho ɡ h; Δ P for points head of liquid and liquid capillary resistance losses, usually respectively. bar； Po— The evaporation pressure, KPa.
, determine the form of a pneumatic valve:
choose to balance within or outside the balance, the pressure drop in the evaporator. R system, when pressure drop exceeds the corresponding evaporation temperature ℃, all appropriate USES outside balanced thermal expansion pneumatic valve.
, and the choice of pneumatic valve type and specification:
calculate according to the Q and the expansion of the pneumatic valve Δ P and evaporation temperature before and after the t in the table by the relevant check pneumatic valve type and the capacity of the pneumatic valve. In order to simplify the selection of the formalities, can also according to the design, the technical measures of the thermal expansion pneumatic valve type and specification, must according to the types of the refrigerants used in refrigeration system, the scope of the evaporation temperature and the size of the heat load of evaporator for, when the choice should meet the following requirements:
( ） The choice of thermal expansion of the pneumatic valve the actual heat load of large - capacity than the evaporator %；
（ ） No adjustive pneumatic valve cooling or cooling water temperature is low in winter of the refrigeration system, choosing thermal expansion pneumatic valve, pneumatic valve capacity should be larger than the evaporator load - %, but shall not exceed the largest evaporator heat load times;
（ ） Choosing thermal expansion pneumatic valve, should be calculated for the fluid pressure drop of pipeline, to draw a pressure difference before and after pneumatic valve, according to the expansion of the factory provided by pneumatic valve capacity table calculation method of thermal expansion of the specifications of the pneumatic valve.
2,
installation, check it before the installation, particularly thermal parts;
, installation location must be close to the evaporator, pneumatic valve should be installed vertically, not tilted or inverted installation;
and when installation, attention should be paid to make the liquid inside the heat organization always stay within the heat pack, so thermal bag should be lower than pneumatic valve is installed;
as much as possible, the thermal bag installed on the evaporator export levels back to the trachea, the general should be far away from the compressor suction mouth. M above;
, thermal bags must not be placed in a fluid from tube road;
if, evaporator export with gas-liquid exchanger, the heat are packing in the evaporator outlet, namely before heat exchanger;
, thermal bags are usually placed on the evaporator muffler, and clingy wall bandage tightly, contact point scale should be clean, bared metal color;
and when the pipe diameter less than mm, thermal bag can be tied in the back to the top of the trachea; When mm in diameter, can be tied in the back to the underside of the trachea °, to prevent the pipe at the bottom of the product oil etc, affect the correct thermal heat packs. Three, debugging,

and evaporator export thermometer or the use of inspiratory pressure to check heat;
, degree of superheat is too small ( For fluid volume is too big, adjust lever clockwise rotation or half a circle a circle, That increase the spring force, reduce the pneumatic valve opening, refrigerant flow rate decrease; Regulating rod thread a turning laps shoulds not be too much, Regulating rod thread turning a circle, about change - over heat ℃, after adjustment for many times, until meet the requirements;
, experience, adjust way: turn the adjusting lever thread change pneumatic valve opening, muffler just can make evaporator frosting or condensation. On the evaporation temperature is lower than the refrigeration unit, if after the frost touched with the hand, there is a will hand sticking to the feeling of cold, the opening is appropriate; For evaporating temperature in degrees above, can according to the condition of condensation.