Rule of Thumb for ME.

Rule of Thumb for Mechanical Engineer.

For Piping Size

#1 Pipe size for condenser water.

    Q (water flow) = 3.2 GPM/TR

     TR = 1 TONS of Refrigeration

    Q = Area x Velocity

    Velocity is given - See Carrier specs/book/google

    A = (pi x d^2)/4 = area of pipe

#2 Pipe size for chilled water

    Q (water flow) = 32.4 GPM/TR

     TR = 1 TONS of Refrigeration

#3 Air Duct

    Q (air flow) = 350 CFM to 400 CFM for 1 TONS of Refrigeration (TR)

    Sample 3TR x 400 CFM = 1200CFM

    It is varying if outside the STP or Normal.

    Normal celling height = 3m.

How to measure capacity? Aircon

#1 For Data Center (sensible cooling electronics parts)

        5 to 10 sqm/TR

#2 For restaurant (Sangyup) high density heat

        8 to 10 sqm/TR 

    e.g. 50sqm / 10sqm/TR = 5TR 

    For medium density heat restaurant Macdo/Jolibee

        12 to 15 sqm/TR

    For light restaurant starbuck

        15 to 178 sqm/TR

    For office (BPO) - highly populated area.

        13 to 16 sqm/TR

    For headquarter office (HQ) less populated

        15 to 18 sqm/TR

    For House room

        measurement (0.8m or 0.5m) hakbang

        30sqm = 1.5HP

        12sqm = 0.5HP

        15sqm = 0.75hp of 1hp

    Living room  spot cooling A/C near SOA

        20sqm up to 25sqm

    Kitchen spot cooling also near the Chef

        20sqm

Comfort cooling of human = 55+/-5 RH relative humidity

                                            = 21 to 25 deg C.

RH (humidity) 40% and below - static electricity

RH (humidity) 60% above - condensation - the conversion of a vapor or gas to a liquid.

What does 40 percent humidity mean?

"Relative Humidity" is the ratio of water vapor present in a given volume of air at a given temperature to the most water vapor the air can hold, expressed as a percent. So 40% relative humidity means 40% saturation of the air.

What happens when RH reaches 100%?

When relative humidity reaches 100 percent or is saturated, moisture will condense, meaning the water vapor changes to liquid vapor. Thus, the saturation level of air is related to the air's temperature. As air temperature increases (or becomes warmer), more water remains in a gas phase.

Board exam tip when you forgot the formula.

1 . Unit analysis

2. Energy balance or mass balance.

AT home to save electricity. Instead of using aircon - use humidifier (electric fan with cool water) but make sure your door is partial open to avoid damaging you laptop electronic parts if the door is close.

Use as many economizer on your design so that you don't throw energy in the air.

What does 2nd law of thermodynamics state?

The second law of thermodynamics states that as energy is transferred or transformed, more and more of it is wasted. It's one of the four laws of thermodynamics, which describe the relationships between thermal energy, or heat, and other forms of energy, and how energy affects matter.

Thermal wheel.

BIO - BREAK

1. unit analysis

2. energy balance or mass balance