96 lines
1.4 KiB
Markdown
96 lines
1.4 KiB
Markdown
---
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id:
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aliases: []
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tags:
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- destiny/uncertain
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- status/incomplete
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- topic/construction/electrical
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- type/encyclopedia
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- authorship/original
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title: HVAC Calculations
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---
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# HVAC Calculations
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## Units
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### British Thermal Unit
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Unit of heat energy
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There are several definitions of the Btu,
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HVAC uses the IT definition,
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abbreviated Btu<sub>IT</sub>
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$$
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\begin{align*}
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1 \text{Btu}_\text{IT} &= \left( 4.1868 \times 453.59237 \times{\frac{5}{9}} \right) \text{J} \\
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&\approx 1055.056 \text{J}
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\end{align*}
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$$
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More common than Btu itself is
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thousand British thermal units per hour (MBH),
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a unit of power.
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$$
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\begin{align*}
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1 \text{MBH} &= 1000 \text{Btu/hr} \\
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&\approx 3.412 \text{W}
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\end{align*}
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$$
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### Ton of Refrigeration (TR or TOR)
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Unit of power
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> [!info] Also Known As
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> * refrigeration ton (RT)
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> * ton (refrigeration)
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$$
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\begin{align*}
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1 \text{TR} &= 12000 \text{Btu}_\text{IT}/\text{h} \\
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&\approx 3516.853 \text{W}
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\end{align*}
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$$
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### Cubic Feet per Minute (CFM)
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Unit of volumetric flow
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## Measures
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### Airflow
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* CFM
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External static pressure (ESP)
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measured in inches of water
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### Heating/Cooling Capacity
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* Tons (refrigeration)
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* MBH
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Entering air temperature (EAT)
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Leaving air temperature (LAT)
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Mixed air temperature (MAT)
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Latent heat
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Sensible heat
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Sensible -> dry bulb
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Latent -> wet bulb
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#### ???
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OSA EAT (F)
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EXH EAT (F)
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IN S.L.
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OUT ALT.
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### Efficiency
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* η (eta)
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