89 lines
3.2 KiB
Swift
89 lines
3.2 KiB
Swift
import Dependencies
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import Foundation
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import Logging
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import PsychrometricClient
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import Routes
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public extension HVACSystemPerformance.Request {
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// TODO: Check if we should use psychrometrics for the request conditions instead
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private static let airDensity = 0.075 // lb/ft^3 at standard conditions.
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private static let specificHeat = 0.24 // BTU/lb at standard conditions (imperial).
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func respond(logger: Logger) async throws -> HVACSystemPerformance.Response {
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@Dependency(\.psychrometricClient) var psychrometricClient
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try validate()
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let altitude = parseAltitude()
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let temperatureSplit = returnAirTemperature - supplyAirTemperature
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let returnAirProperties = try await psychrometricClient.psychrometricProperties(.dryBulb(
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.init(.init(returnAirTemperature)),
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relativeHumidity: returnAirHumidity%,
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altitude: altitude
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))
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let supplyAirProperties = try await psychrometricClient.psychrometricProperties(.dryBulb(
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.init(.init(supplyAirTemperature)),
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relativeHumidity: supplyAirHumidity%,
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altitude: altitude
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))
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let airMassFlow = airflow * 60 * Self.airDensity
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logger.debug("Air mass flow: \(airMassFlow)")
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let condensationRate = airMassFlow * (
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returnAirProperties.humidityRatio.value - supplyAirProperties.humidityRatio.value
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) // lb/hr
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let sensibleCapacity = airMassFlow * Self.specificHeat * temperatureSplit
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logger.debug("Return enthalpy: \(returnAirProperties.enthalpy.value)")
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logger.debug("Supply enthalpy: \(supplyAirProperties.enthalpy.value)")
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let deltaEnthalpy = returnAirProperties.enthalpy.value - supplyAirProperties.enthalpy.value
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logger.debug("Delta enthalpy: \(deltaEnthalpy)")
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let totalCapacity = airMassFlow * deltaEnthalpy
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let capacity = HVACSystemPerformance.Capacity(
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total: totalCapacity,
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sensible: sensibleCapacity,
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latent: totalCapacity - sensibleCapacity
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)
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let systemMetrics = HVACSystemPerformance.SystemMetrics(
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cfmPerTon: airflow / systemSize,
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targetTemperatureSplit: (systemSize * 12000 * 0.75) / (1.08 * airflow),
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actualTemperatureSplit: temperatureSplit,
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condensationRatePoundsPerHour: condensationRate
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)
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return .init(
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returnAirProperties: returnAirProperties,
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supplyAirProperties: supplyAirProperties,
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capacity: capacity,
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systemMetrics: systemMetrics
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)
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}
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private func parseAltitude() -> Length {
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guard let altitude, altitude > 0 else { return .seaLevel }
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return .init(altitude)
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}
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private func validate() throws {
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guard returnAirTemperature > 0 else {
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throw ValidationError(message: "Return air temperature should be greater than 0.")
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}
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guard returnAirHumidity > 0 else {
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throw ValidationError(message: "Return air humidity should be greater than 0.")
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}
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guard supplyAirTemperature > 0 else {
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throw ValidationError(message: "Supply air temperature should be greater than 0.")
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}
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guard supplyAirHumidity > 0 else {
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throw ValidationError(message: "Supply air humidity should be greater than 0.")
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}
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guard systemSize > 0 else {
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throw ValidationError(message: "System size should be greater than 0.")
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}
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}
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}
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