Otis Elevator Scada Engineer Interview Questions and Answers

Sub cooling in air conditioning is the process of cooling the refrigerant below its saturation temperature to improve system efficiency.

• Sub cooling increases the efficiency of the air conditioning system by ensuring the refrigerant is in a liquid state before entering the expansion valve.

• It helps in preventing flash evaporation of the refrigerant, which can lead to inefficiencies in the system.

• Sub cooling is typically ...read more

ISEER rating is calculated based on the weighted average of the cooling performance of an air conditioner under different conditions.

• ISEER = (Weighted Cooling Capacity at 100% load x 0.4) + (Weighted Cooling Capacity at 75% load x 0.2) + (Weighted Cooling Capacity at 50% load x 0.4)

• The higher the ISEER rating, the more energy efficient the air conditioner is.

• ISEER rating helps consumers compare the energy efficiency of...read more

The refrigeration cycle is a thermodynamic cycle used in refrigerators and air conditioning systems to transfer heat from a low temperature to a high temperature environment.

• The cycle consists of four main components: compressor, condenser, expansion valve, and evaporator.

• The refrigerant enters the compressor as a low-pressure gas and leaves as a high-pressure, high-temperature gas.

• The high-pressure gas then flows into...read more

Mainstream refrigerants used in household air conditioning include R-410A, R-22, and R-134a.

• R-410A is a popular refrigerant known for its high efficiency and environmental friendliness.

• R-22, although being phased out due to its ozone-depleting properties, is still commonly found in older air conditioning systems.

• R-134a is commonly used in automotive air conditioning systems but can also be found in some household units

1 ton cooling concept refers to the amount of heat required to melt one ton of ice in a 24-hour period.

• 1 ton of cooling is equal to 12,000 BTUs per hour

• It is commonly used in the HVAC industry to measure the cooling capacity of air conditioning systems

• For example, a 2-ton air conditioner can remove 24,000 BTUs of heat per hour

The relationship between current, voltage, and power is described by Ohm's Law, which states that current is directly proportional to voltage and inversely proportional to resistance.

• Ohm's Law states that V = I * R, where V is voltage, I is current, and R is resistance.

• Power (P) is calculated using the formula P = V * I, where P is power, V is voltage, and I is current.

• In a circuit with a constant resistance, an increa...read more

1 BTU is approximately equal to 0.29307107 watts. To convert BTU to watts, multiply by 0.29307107. To convert watts to BTU, divide by 0.29307107.

• 1 BTU = 0.29307107 watts

• To convert BTU to watts, multiply by 0.29307107

• To convert watts to BTU, divide by 0.29307107

Types of process include batch process, continuous process, and hybrid process.

• Batch process involves processing a set amount of materials at one time

• Continuous process involves ongoing production without interruption

• Hybrid process combines elements of both batch and continuous processes