Equations Factors
Fans & Laws
| cfmn/ cfmo | = | (rpmn/ rpmo) |
| spn/ spo | = | (rpmn/ rpmo)2 |
| hpn/ hpo | = | (rpmn/ rpmo)3 |
| rpm driven * diameter driven | = | rpm driver * diameter driver |
| Percent Outdoor Air | = | (RAT - MAT) / (RAT - OAT) |
Motors
| Percent Load | = | (NLRPM - RPM) / (NLRPM - FLRPM) |
| Synchronous Speed | = | (frequency * 60) / (number of pole pairs) |
Lighting
| RCR | = | (2.5 * cavity height * perimeter) / (area) |
| Number of Lamps | = | (FC desired * area) / (Lumens per Lamp * Cu * L1* L2) |
| FC | = | Lumens / d2 |
| Efficiency | = | Lumens / watt |
Electrical
| Hp * Percent load | = | (V * A * 1.73 * PF * Effeciency) / 746 |
| PF | = | kW / kVa |
Heat Flow
| q | = | u * A * Δt of conduction |
| q | = | A * Shading Coefficient * Solar Gain |
| Q Cooling | = | U * A * 24 * CDD |
| Q Heating | = | U * A * 24 * HDD |
Miscellaneous
| Velocity Air Pressure: | "H2O = (fpm / 4005)2 |
| Cv: Flow in GPM through a valve or piece of equipment with a pressure difference of 1 psi. | gpm = Cv * V * ΔP |
| A ton of refrigeration is the equivalent to convert one ton of ice to water in 24 hours. | Ton = 288,000 Btu / day Ton = 12,000 Btu / hr |
| KVA (3 Phase) | = | V * I * 1.73 1000 |
Where: |
| KW (3 Phase) | = | V * I * 1.73 * Pf 1000 |
Where: |
| psia | = | psig + 14.7 | |
| q | = | cfm * 1.08 * Δt | (sensible heat for air) Btu/hr |
| q | = | gpm * 500 Δt | (sensible heat for water) Btu/hr |
| COP | = | EER / 3.412 | |
| Btu | = | heat 1lb water from 59°F to 60°F | |
| Heat Cap H20 | = | 1 Btu / lb °F | |
| Fuel Cost | = | ( Output / Efficiency ) * (Cost Per Unit) | |
| Density of Dry Air at Standard Conditions | = | 0.075 lb/ft3 | |
| Specific heat of Dry Air at Standard Conditions | = | 0.24 Btu / lb°F | |
| Density of Water at Standard Conditions | = | 8.34 lb / gal | |
| Specific Heat of Water at Standard Conditions | = | 1 Btu / lb°F | |
| Water | = | 7.48 gal = 1 Cubic Foot | |
| Efficiency | = | Output Power Input Power |
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