Energy Efficiency Ratio EER !By Imran

Energy Efficiency Ratio EER The Energy Efficiency Ratio - EER - is a term generally used to define cooling energy efficiency of unitary air-conditioning and heat pump system.

The efficiency is determined at a single rated condition specified by an appropriate equipment standard and is defined as the ratio of net cooling capacity - or heat removed in Btu - to the total input rate of electric energy applied - in Wh. The units of EER are Btu/Wh. EER = Qc / E (3) where EER = energy efficient ratio (Btu/Wh) Qc = net cooling energy (Btu) E = applied electrical energy (Wh) This efficiency term typically includes the energy requirement of auxiliary systems such as the indoor and outdoor fans. higher EER - more efficient system Example - EER for an Air Conditioner Unit The heat removed and electrical power consumed for the air conditioner unit can be measured and calculated in different ways. One simple alternative is to calculate mean values from some . The heat removed for 3 hours can be estimated to Qc = ((8500 Btu/h + 10000 Btu/h + 7000 Btu/h) / 3) (3 h) = 25500 Btu The electrical consumption for 3 hours can be estimated to E = ((600 W + 700 W + 550 W) / 3) (3 h) = 1850 Wh EER for the air conditioner unit can be estimated to EER = (25500 Btu) / (1850 Wh) = 13.8 Thanks for read if you want to anything related to HVAC and Mechanical Engineering then comments and subscribe for new update.

How to calculate Duct Air Flow in CFM with help of Pressure Sensor ! By Imran

Determining Duct Air Flow in CFM using to Pressure Sensor by Imran

To calculate Air Flow in Cubic Feet per Minute (CFM), determine the Flow Velocity in feet per minute, then multiply this figure by the Duct Cross Sectional Area. Air Flow in CFM (Q) = Flow Velocity in Feet Per Minute (V) x Duct Cross Sectional Area (A) Determining Flow Velocity The easiest way to determine Flow Velocity is to measure the Velocity Pressure in the duct with a Pitot Tube Assembly connected to a differential pressure sensor. The Pitot Tube Assembly includes a Static Pressure Probe and a Total Pressure Probe. A Total Pressure Probe, aligned into the airflow, senses the duct velocity pressure and the static pressure, which equals the total pressure. A Static Pressure Probe aligned at a right angle to the airflow senses only the static pressure. The difference between the total pressure reading and the static pressure reading is the Velocity Pressure. If you connect the Total Pressure Probe to the HIGH port on a differential pressure sensor and the Static Pressure Probe to the LOW port on the differential pressure sensor, then the sensor’s output will be the Velocity Pressure, as shown in the figures below. Fig. 1: BAPI Pitot Tube Assembly, includes Static and Total Pressure Probe Assemblies (ZPS-ACC12) Fig. 2: BAPI Differential Zone Pressure Sensor (ZPS) measuring Velocity Pressure The Flow Velocity is then determined with the following equation: V = 4005 x √ΔP V = Flow Velocity in feet per minute. √= Square root of the number to the right . ΔP = The Velocity Pressure measured by the pressure sensor Example: Measuring a Velocity Pressure of .75” W.C. equals a Flow Velocity of 3,468 Ft/Min. V = 4005 x √0.75 √0.75 = 0.866 • 4005 x 0.866 = 3,468 • Flow Velocity = 3,468 Ft/Min Determining Duct Cross Sectional Area After obtaining the Flow Velocity from the previous procedure, that figure is now multiplied by the Duct Cross Sectional Area to determine the Air Flow in CFM. There are two different equations for determining the Duct Cross Sectional Area, one for round ducts and one for square or rectangular ducts. The equation for square or rectangular ducts is: A = X x Y A = Duct Cross Sectional Area X = Duct height in feet Y = Duct width in feet. The equation for a round duct is: A = π x r² A = Duct Cross Sectional Area π= 3.14159 r = radius of duct in feet Example: An 18” diameter round duct has a Duct Cross Sectional Area of 1.77 Ft² A = π x r² or A = 3.14158 x .5625 18” diameter is 1.5 feet, therefore the radius is .75 feet • r² = 0.75² = 0.5265 • π = 3.14159 A = 3.14159 x 0.5625 = 1.77 Ft² Determining Air Flow in CFM After obtaining the Flow Velocity and the Duct Cross Sectional Area from the previous two procedures, the Air Flow in CFM is determined by multiplying the two: Air Flow in CFM (Q) = Flow Velocity in Feet Per Minute (V) x Duct Cross Sectional Area (A) Example: An 18” diameter round duct with a Velocity Pressure of .75” W.C. has an Air Flow of 6,128 CFM The Flow Velocity is 3,468 Ft/Min. V = 4005 x √ΔP) V = 4005 x √0.75) √0.75 = 0.866 • 4005 x 0.866 = 3,468 • Flow Velocity = 3,468 Ft/Min The Duct Cross Sectional Area is 1.77 Ft² A = π x r² π= 3.14159 • r² = 0.75² = 0.5625 Duct Cross Sectional Area (A) = 3.14159 x 0.5625 = 1.77 Ft² The Air Flow in CFM is 6,128 Ft³/Min Air Flow in CFM (Q) = Flow Velocity in Feet Per Minute (V) x Duct Cross Sectional Area (A) Air Flow in CFM (Q) = 3,468 Ft/Min x 1.77 Ft² = 6,128 CFM. Thanks for read if you want to anything related to HVAC and Mechanical Engineering then comments and subscribe for new update.

Chiller Chemical dosing system water treatment! By Imran

Chemical treatment (or dosing):

Proprietary (like NALCOOL) or generic chemicals (like Sodium Silicate, Sodium Nitrite, and Sodium Sulfite) compositions are used to prevent the chiller system from corrosion, scaling, fouling and microbiological growth. How? Mainly in three ways: first, these chemicals react with the pipes to form a protective thin inside layer; second, the chemicals help in maintaining the pH level; and third, the chemicals remove corrosive dissolved oxygen in the water. Dosing pumps are used for applying the predetermined quantities of chemicals at regular intervals. Mechanical Treatment: Before commissioning, the whole system should be cleaned and flushed using treated water and commission it as soon as possible. Attend all the leaking points regularly. Filtration: The filter is used for removing (or at least reducing) the solid particles (like welding flush, concrete particles, etc.). UV and Ozone treatment: This method is effective for preventing the microbiological growth in the system, but is not used widely for chillers unless there is some restriction for chemical treatment. Unlike chemical dosing, this treatment does not generate harmful chemical by-products. Thanks for read if you want to anything related to HVAC and Mechanical Engineering then comments and subscribe for new update.

What is (DX )direct expansion air conditioning unit!By Imran

direct expansion air conditioning unit, also called a DX unit, cools indoor air using a condensed refrigerant liquid. It is the type of air conditioning unit most commonly used in homes in the United States.

Direct Expansion Cooling The unit cools air by passing the condensed refrigerant through a heat exchanger inside the building to be cooled. In this part of the unit, called the evaporator, the refrigerant expands as it absorbs heat, eventually converting to a gas. The unit then pumps the refrigerant to a compressor, which compresses the gas and passes it through another heat exchanger, the condenser, outside the building. The heat that has been absorbed by the refrigerant is released to the outdoor air, and the cooled, compressed refrigerant is once again in liquid form. The unit pumps the cooled refrigerant liquid back to the evaporator and the cycle begins again.