- It is used in large evaporators , where pressure drop take place at the end of evaporator ie, more than 0.3 bar
- The pressure acting outsode the bellow from heat sensing bulb and capillary tube is total of the saturation pressure plus superheat . This pressure is trying to open the valve , overcoming the spring pressure.
- The equilizing line has saturation pressure at the end of an evaporator coil acting from the bottom of the bellow ( diaphram ) . Hence the saturation pressure from equalizing line and capilliary tube is balancing each other.
- The additional pressure from outside of bellow due to superheat is now reaponsible to open the expansion valve. By this arrangement , we are getting actual degree of superheat . Correct degree of superheat ensure that refrigerant is used efficiently and no liquid reaches to compressor suction . Also evaporator shoulf not starved of refrigerant.
1. High cost: Manganese bronze is a costly alloy, making it less economical for large propellers. 2. Low strength-to-weight ratio: Compared to other propeller materials like nickel-aluminum bronze or stainless steel, manganese bronze has a lower strength-to-weight ratio. 3. Susceptible to corrosion: Manganese bronze can corrode in seawater, especially when exposed to high velocities and turbulence. 4. Poor cavitation resistance: Manganese bronze is more prone to cavitation damage than other materials. 5. Difficult to cast and machine: Manganese bronze is challenging to cast and machine, making it less desirable for complex propeller geometries. 6. Limited weldability: Manganese bronze has poor weldability, making repairs and modifications difficult. Nickel-aluminum bronze or stainless steel are commonly used for propellers due to their: - High strength and durability - Excellent corrosion resistance - Good cavitation resistance - Ease of casting and machining - Weldability
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