VFD

A Variable Frequency Drive (VFD) is a type of motor controller that drives an electric motor by varying the frequency and voltage supplied to the electric motor. Other names for a VFD are variable speed drive, adjustable speed drive, adjustable frequency drive, AC drive, microdrive, and inverter. ---------------------- Mohammad Imran HVAC Engineer

Compressor Over load

The overload relay is a protection device used in the compressor circuit on your refrigerator. Power is applied to the compressor motor windings through the overload device, and the relay is used to add the start winding in the circuit until the compressor is at running speed. ----------------------- Mohammad Imran HVAC Engineer

What is surge

In a centrifugal compressor, 'surge' is a name given to a dangerously unstable gas condition in the compressor and condenser. Put simply, it occurs when the forward compression thrust of gases in the compressor wheel falls below the critical velocity of the gas to flow forward through the condenser.Apr

Cause of surging in chiller

The flow separation will eventually cause a decrease in the discharge pressure, and flow from suction to discharge will resume. Surging can cause the compressor to overheat to the point at which the maximum allowable temperature of the unit is exceeded. ... This is defined as the surge cycle of the compressor.. --------------------- Mohammad Imran HVAC Engineer

Water treatment process

Community Water Treatment Drinking water supplies in the United States are among the safest in the world. However, even in the U.S., drinking water sources can become contaminated, causing sickness and disease from waterborne germs, such as Cryptosporidium, E. coli, Hepatitis A, Giardia intestinalis, and other pathogens. Drinking water sources are subject to contamination and require appropriate treatment to remove disease-causing agents. Public drinking water systems use various methods of water treatment to provide safe drinking water for their communities. Today, the most common steps in water treatment used by community water systems (mainly surface water treatment) include: Figure illustrating the water treatment cycle, showing coagulation, sedimentation, filtration, and disinfection Figure courtesy of EPA Coagulation and Flocculation Coagulation and flocculation are often the first steps in water treatment. Chemicals with a positive charge are added to the water. The positive charge of these chemicals neutralizes the negative charge of dirt and other dissolved particles in the water. When this occurs, the particles bind with the chemicals and form larger particles, called floc. Sedimentation During sedimentation, floc settles to the bottom of the water supply, due to its weight. This settling process is called sedimentation. Filtration Once the floc has settled to the bottom of the water supply, the clear water on top will pass through filters of varying compositions (sand, gravel, and charcoal) and pore sizes, in order to remove dissolved particles, such as dust, parasites, bacteria, viruses, and chemicals. Disinfection After the water has been filtered, a disinfectant (for example, chlorine, chloramine) may be added in order to kill any remaining parasites, bacteria, and viruses, and to protect the water from germs when it is piped to homes and businesses.

Role of vacuum in RAC

A vacuum is maintained in the condenser so that steam can easily flow and more work can be extracted from the steam in the turbine. How does the condensate extraction pumps take suction from such a low pressure condensor. ---------------'-----' Mohammad Imran HVAC Engineer