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Update Rule22-17.md #1388

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Update Rule22-17.md
KarenWGard Jun 19, 2024
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Update Rule22-17.md
KarenWGard Dec 4, 2024
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Update Rule22-17.md
KarenWGard Dec 11, 2024
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31 changes: 16 additions & 15 deletions docs/section22/Rule22-17.md
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@@ -1,7 +1,7 @@

# CHW&CW - Rule 22-17

**Schema Version:** 0.0.25
**Schema Version:** 0.0.37
**Mandatory Rule:** FALSE
**Rule ID:** 22-17
**Rule Description:** The baseline heat rejection device shall have an efficiency of 38.2 gpm/hp
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## Rule Logic:

- set has_fan_shaft_power flag equal to false: `has_fan_shaft_power = false`
- set has_fan_motor_nameplate_power flag equal to false: `has_fan_motor_nameplate_power = false`

- create a variable additional_note_for_no_shaft_power. If the heat_rejection has the fan_shaft_power data element, this note variable will be a blank string, however if there is no fan_shaft_power, the note will be a string that describes how fan_shaft_power is calculated: `set additional_note_for_no_shaft_power = ""`
- create a variable additional_note_for_motor_nameplate_power. If the heat_rejection has the fan_motor_nameplate_power data element, this note variable will be a blank string, however if there is no fan_motor_nameplate_power, the note will be a string that describes how fan_shaft_power is calculated: `set additional_note_for_motor_nameplate_power = ""`

- check if the heat rejection has fan_shaft_power (not sure the exact python command for this): `if heat_rejection.fan_shaft_power:
- check if the heat rejection has fan_motor_nameplate_power (not sure the exact python command for this): `if heat_rejection.fan_motor_nameplate_power:
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missing `


- set fan_shaft_power equal to heat_rejection.fan_shaft_power: `fan_shaft_power = heat_rejection.fan_shaft_power`
- set fan_motor_nameplate_power equal to heat_rejection.fan_motor_nameplate_power: `fan_motor_nameplate_power = heat_rejection.fan_motor_nameplate_power`

- set has_fan_shaft_power flag equal to true: `has_fan_shaft_power = true`
- set has_fan_motor_nameplate_power flag equal to true: `has_fan_motor_nameplate_power = true`

- otherwise, we need to calculate shaft power based on the motor nameplate power: `else:`
- otherwise, we need to calculate shaft power based on the motor nameplate power if fan_shaft_power is defined: `elif heat_rejection.fan_shaft_power:`

- set fan_shaft_power equal to the heat_rejection.fan_motor_nameplate_power * 0.9 (0.9 is a rule of thumb suggested by Michael Rosenberg in April 2023): `fan_shaft_power = heat_rejection.fan_motor_nameplate_power * 0.9 * heat_rejection.fan_motor_efficiency`
- set fan_motor_nameplate_power equal to the heat_rejection.fan_shaft_power * 0.9 (0.9 is a rule of thumb suggested by Michael Rosenberg in April 2023): `fan_motor_nameplate_power = heat_rejection.fan_shaft_power * 0.9 * heat_rejection.fan_motor_efficiency`
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@claperle claperle Nov 25, 2024 •
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I was finding this confusing because at first when I reviewed this I assumed this meant fan motor nameplate hp but when I got to the end realized it means fan motor nameplate power in kW. I suppose that makes sense but I think hp is much more commonly reported on motor nameplates than kW although the baseline is a virtual motor any way so maybe what is commonly reported on motors does not matter then.

To go from fan_shaft_power to motor nameplate power I think this should be *(1/0.9)

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@claperle claperle Nov 25, 2024 •
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Also, in the schema the note on the right says nameplate hp.

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ok, updated the calculation for fan_BHP to be different depending on whether fan_motor_nameplate_power exists. If fan_motor_nameplate_power exists, then fan_BHP = fan_motor_nameplate_power

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I am not following this, why would fan_BHP equal fan_motor_nameplate_power?

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@claperle claperle Dec 4, 2024 •
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@KarenWGard I recommend that we discuss these comments before edits are made to avoid multiple iterations resulting from miscommunications.


- if the shaft power is not directly entered, we also need to create an additional note to return with the result, describing how the calculation was completed: `addtitional_note_for_no_shaft_power = " *Note: The fan shaft power for " + heat_rejection + " was not given. For this evaluation, the fan shaft power was cacluated using a rule of thumb where fan_shaft_power = fan_motor_nameplate_power * 0.9 * fan_motor_efficiency."

- calculate fan brake horsepower by multiplying the fan shaft power by 0.00134102 (the conversion from Watts to HP): `fan_BHP = fan_shaft_power * 0.00134102`
- if the motor nameplate power is not directly entered, we also need to create an additional note to return with the result, describing how the calculation was completed: `addtitional_note_for_no_motor_nameplate_power = " *Note: The fan motor nameplate power for " + heat_rejection + " was not given. For this evaluation, the fan motor nameplate power was cacluated using a rule of thumb where fan_motor_nameplate_power = fan_shaft_power * 0.9 * fan_motor_efficiency."
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@claperle claperle Nov 25, 2024 •
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Missing `

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To go from fan_shaft_power to motor nameplate power I think this should be *(1/0.9)


- otherwise, if there is no fan motor nameplate power or no fan_shaft power, then we can't calculate at all, set a boolean: could_not_calculate to TRUE: `could_not_calculate = true`
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@claperle claperle Nov 25, 2024 •
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Need
else:
could_not_calculate = True

- calculate fan brake horsepower by multiplying the fan shaft power by 0.00134102 (the conversion from Watts to HP): `fan_BHP = fan_motor_nameplate_power * 0.00134102`

- get the rated water flow rate (assumed to be gpm): `rated_water_flowrate = heat_rejection.rated_water_flowrate`

- calculate the efficiency in gpm/hp: `heat_rejection_efficiency = rated_water_flowrate / (fan_BHP)`

**Rule Assertion - HeatRejection:**

- Case 1: check if the efficiency is greater than the rated efficiency: `if ( ahj_flag AND ( heat_rejection_efficiency > 38.2 )): UNDETERMINED; note = "The project includes a cooling tower. We calculated the cooling tower efficiency to be " + heat_rejection_efficiency + ", which is greater than the required efficiency of 38.2 gpm / hp, resulting in a more stringent baseline. However, it was not possible to verify that the modeling inputs correspond to the rating conditions in Table 6.8.1-7." + addtitional_note_for_no_shaft_power`
- Case 1: the result couldn't be calcualted because fan_motor_nameplate_power and fan_shaft_power were not given: `if could_not_calculate: UNDETERMINED; note = "The project includes a cooling tower. However, we could not calculate the cooling tower efficiency because neither the fan_motor_nameplate_power nor fan_shaft_power were given"
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missing `

- Case 2: check if the efficiency is greater than the rated efficiency: `if ( ahj_flag AND ( heat_rejection_efficiency > 38.2 )): UNDETERMINED; note = "The project includes a cooling tower. We calculated the cooling tower efficiency to be " + heat_rejection_efficiency + ", which is greater than the required efficiency of 38.2 gpm / hp, resulting in a more stringent baseline. However, it was not possible to verify that the modeling inputs correspond to the rating conditions in Table 6.8.1-7." + additional_note_for_motor_nameplate_power`

- Case 2: elsif the heat_rejection_efficiency equals 38.2 gpm/hp, PASS, but include note: `if ( heat_rejection_efficiency == 38.2 ): UNDETERMINED; note = "The project includes a cooling tower. We calculated the cooling tower efficiency to be correct at 38.2 gpm / hp. However, it was not possible to verify that the modeling inputs correspond to the rating conditions in Table 6.8.1-7." + addtitional_note_for_no_shaft_power`
- Case 3: elsif the heat_rejection_efficiency equals 38.2 gpm/hp, PASS, but include note: `if ( heat_rejection_efficiency == 38.2 ): UNDETERMINED; note = "The project includes a cooling tower. We calculated the cooling tower efficiency to be correct at 38.2 gpm / hp. However, it was not possible to verify that the modeling inputs correspond to the rating conditions in Table 6.8.1-7." + additional_note_for_motor_nameplate_power`
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The description says PASS but the outcome is UNDETERMINED.


- Case 3: Else: `else: UNDETERMINED; note = "The project includes a cooling tower. We calculated the cooling tower efficiency to be " + heat_rejection_efficiency + ", which is less than the required efficiency of 38.2 gpm / hp. However, it was not possible to verify that the modeling inputs correspond to the rating conditions in Table 6.8.1-7. Please review the efficiency and ensure that it is correct at the rating conditions as specified in the Table 6.8.1-7." + addtitional_note_for_no_shaft_power`
- Case 4: Else: `else: UNDETERMINED; note = "The project includes a cooling tower. We calculated the cooling tower efficiency to be " + heat_rejection_efficiency + ", which is less than the required efficiency of 38.2 gpm / hp. However, it was not possible to verify that the modeling inputs correspond to the rating conditions in Table 6.8.1-7. Please review the efficiency and ensure that it is correct at the rating conditions as specified in the Table 6.8.1-7." + additional_note_for_motor_nameplate_power`


**Notes:**
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