Which of these is a disadvantage of open heater? Explanation: The disadvantage is the necessity of a pump at each heater to handle the large feedwater stream. 12.

Why at least one open heater is used? Explanation: The open heater works as a deaerator.

Heat transfer in closed feedwater heaters is less effective since the two streams are not allowed to be in direct contact. Most steam power plants use a combination of open and closed feedwater heaters. A steam power plant with one open and three closed feedwater heaters.

A feedwater economizer reduces steam boiler fuel requirements by transferring heat from the flue gas to incoming feedwater. Boiler flue gases are often rejected to the stack at temperatures more than 100°F to 150°F higher than the temperature of the generated steam. The stack temperature is measured at 500°F.

Economizers (US and Oxford spelling), or economisers (UK), are mechanical devices intended to reduce energy consumption, or to perform useful function such as preheating a fluid. The term economizer is used for other purposes as well.

An economizer is a part of a building’s cooling system that uses cool outdoor air to cool the building instead of operating the air conditioning compressor. An economizer is an add-on feature to an HVAC air handler that draws in outdoor air and mixes it with return air from indoors.

The economizer modulates exhaust air, return air and outside air dampers to maintain the mixed air temperature at its setpoint (around 60ºF.) The action of the outside air damper and relief damper, if there is one, should always be opposite that of the return air damper.

An economizer is part of rooftop package units—the most common type of HVAC system for businesses. Essentially, if it isn’t too hot inside your building, the economizer allows the refrigerant-based AC to take a break while the outdoor air does most of the work.

An economizer control is a mechanical device that uses cool outside air to cool inside a building, thus reducing the need for electrical cooling. An air conditioner uses electricity at three major components: the compressor; the condenser fan(s); and the evaporator or supply air fan(s).

What is the purpose of the economizer system in a float carburetor? The economizer is essentially a valve which is closed at throttle settings below 60% to 70% of rated power, but provide additional fuel for cooling the engine to prevent detonation at higher throttle settings.

The chief disadvantage of the float carburetor, however, is its icing tendency. Since the float carburetor must discharge fuel at a point of low pressure, the discharge nozzle must be located at the venturi throat, and the throttle valve must be on the engine side of the discharge nozzle.

There are currently more than 30,000 accelerators in operation around the world. There are two basic classes of accelerators: electrostatic and electrodynamic (or electromagnetic) accelerators. Electrostatic accelerators use static electric fields to accelerate particles.

With the throttle open enough so that the main discharge nozzle is operating, fuel does not flow out of the idling jet. As soon as the throttle is closed far enough to stop the spray from the main discharge nozzle, fuel flows out the idling jet.

The idle mixture screw controls the air fuel mixture at idle speed, and often is located near the throttle plate.

Which of the following causes a single diaphragm accelerator pump to discharge fuel? A) An increase in manifold pressure that occurs when the throttle valve is opened. B) An increase in venturi suction when the throttle valve is open….M.8.6.8.2.A.1.

Carburetors are normally calibrated at sea-level air pressure where the correct fuel-air mixture ratio is established with the mixture control set in the FULL RICH position. However, as altitude increases, the density of air entering the carburetor decreases, while the density of the fuel remains the same.

If you plan a flight based on those figures and don’t lean the mixture, you could run out of fuel. When you adjust the fuel/air mixture, you are decreasing fuel flow to the engine to compensate for decreased air density at higher altitudes. Less fuel is needed for proper engine operation as altitude is gained.

However, an over-lean mixture can foul spark plugs and combustion chambers because of cylinder misfiring. Many older engines are equipped with non-alloy steel exhaust valves.

Any mixture greater than 14.7:1 is considered a lean mixture; any less than 14.7:1 is a rich mixture – given perfect (ideal) “test” fuel (gasoline consisting of solely n-heptane and iso-octane).

If the ratio is too rich or too lean, the engine will not burn optimally burn the air-fuel mixture which can cause performance issues or use up too much fuel. But at some conditions, not all fuel can be mixed and vaporized with air.