[م/ طوني جعجع]

هذه المشاركة ذات صلة بملتقى المهندسين العرب : http://www.arab-eng.org/vb/showthrea...#ixzz1wTyuQBNz



The cooling tower
industry
United Smat Company
.

United Smat
company
manufactures
cooling tower
that works
with ammonia
.

The cooling tower
industry
is
in a factory
the company
In Saudi Arabia - Jeddah


- united smat Ammonia Refrigeration – cooling tower



Note the horizontal dashed line in Figure 1. All portions of the system above this line are part of the system high side – those components operating under a high(er) pressure than the pressure within the system low side. As the absolute pressure of a gas increases, its temperature increases, therefore the system high side is usually hot or at least warm to the touch. Everything residing below the dashed line operates under a low(er) pressure than the high side. The pressure difference is a function of the temperatures involved in the process and the refrigerant selected.
Starting at the discharge connection of the compressor, line 1 conveys a high pressure superheated hot gas where it enters a heat exchanger (the condenser). After entering, the gas is first desuperheated. Upon reaching its saturation temperature, the vapor then begins to condense, changing from a vapor state back into a liquid state. If additional heat is removed from this liquid stream, the process is known as "subcooling"[1].
Line 2 conveys the high pressure refrigerant liquid stream from the condenser into an expansion device. There are many different types of expansion devices; in the following short list, I’ve divided these into modulating devices and fixed devices.
Capillary tubes (fixed)
Orifices (fixed, short orifice, Accurator)
Electronic expansion valves (modulating, senses refrigerant temperature rise across evaporator)
Thermal expansion valves (modulating, senses refrigerant superheat generated within evaporator)
Hand expansion valves (fixed but manually readjustable)
High-side floats (modulating, senses liquid level)
Liquid control valves (usually positioned by a remote high side float)
Expansion devices numbered 1 through 4 are commonly applied in halocarbon refrigeration systems. Devices numbered 4 though 7 are used as throttling devices in industrial refrigeration systems and practices.
After leaving the expansion device, the refrigerant has now become a mixture of low pressure cold liquid and vapor as it travels down line 3. In most cases, especially with halocarbon units, this line is very short – maybe an inch or two long. This mixture then enters an evaporator where the remaining liquid is boiled away while transferring heat energy across the evaporator tubing (and fins if they exist). If the expansion device measures refrigerant superheat (or a temperature rise) occurring within the evaporator, the gaseous refrigerant is then superheated slightly before it leaves the evaporator and enters line 4.
Line 4 (also known as suction) conveys the now slightly superheated low pressure vapor back into the compressor where its pressure and temperature are simultaneously raised to a level where heat can be rejected from the condenser into a heat sink (air, water).
When looking at Figure 1, this energy balance becomes apparent:
(1)
: "Denkmann, the system has to balance. The sum of the gozoutas minus the sum of the gozintas has to be equal to zero". All fine and well, I’d say. The bloody thing has to balance.

[السفير77]

تحية طيبة مبادرة جميلة استمر في خدمة العلم والمنتدى تحياتي


السفير77