Update Rule22-17.md #1388
Update Rule22-17.md #1388
Conversation
KarenWGard
requested review from
JasonGlazer,
supriyagoel,
weilixu,
claperle and
JacksonJ-KC
docs/section22/Rule22-17.md
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| - 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: |
docs/section22/Rule22-17.md
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| - 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." | ||
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| - 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." |
docs/section22/Rule22-17.md
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| - 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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| - 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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Need
else:
could_not_calculate = True
docs/section22/Rule22-17.md
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| - 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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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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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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@KarenWGard I recommend that we discuss these comments before edits are made to avoid multiple iterations resulting from miscommunications.
docs/section22/Rule22-17.md
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| - 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." | ||
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| - 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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To go from fan_shaft_power to motor nameplate power I think this should be *(1/0.9)
docs/section22/Rule22-17.md
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| - get the rated water flow rate (assumed to be gpm): `rated_water_flowrate = heat_rejection.rated_water_flowrate` | ||
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| - calculate the efficiency in gpm/hp: `heat_rejection_efficiency = rated_water_flowrate / (fan_BHP)` | ||
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| **Rule Assertion - HeatRejection:** | ||
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| - 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" |
docs/section22/Rule22-17.md
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| - 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.
docs/section22/Rule22-17.md
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| - 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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| - 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` |
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General concept:
Nameplate hp = BHP * LF, we are assuming an LF of 90%
In addition, For purposes of Table 6.8.1-7 and the App G req, cooling tower performance is defined as the water flow rating of the tower at the thermal rating condition listed in Table 6.8.1-7 divided by the fan motor nameplate [horse] power. So the hp in the 38 GPM/hp is nameplate motor hp.
Other thing to keep in mind is that the schema reports fan_motor_nameplate_power in Watts for SI. Need to divide by 0.746 to convert Watts to nameplate HP. If it is reported in HP (IP units) no conversion needed and it is just GPM/fan_motor_nameplate_power.
Motor nameplate hp (IP units) = fan_shaft_power (hp, IP units)/LF with LF = 90% (I don't think we can use this since it is not in 90.1)
Pass and Fail if motor nameplate power is provided. UNDERTERMINED if only shaft power is provided with note explaining the GPM/hp assumign 90% LF.
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