psychart/dist/psychart/psystate.js

View air conditions on a psychrometric chart

import * as SMath from 'smath';
import Psychrolib from 'psychrolib';
/**
 * Represents a single air condition using several states.
 */
export class PsyState {
    state;
    options;
    /**
     * Calculation tolerance
     */
    static TOL = 0.01;
    /**
     * Dry Bulb
     */
    db;
    /**
     * Relative Humidity
     */
    rh;
    /**
     * Wet Bulb
     */
    wb;
    /**
     * Dew Point
     */
    dp;
    /**
     * Humidity Ratio
     */
    hr;
    /**
     * Vapor Pressure
     */
    vp;
    /**
     * Moist Air Enthalpy
     */
    h;
    /**
     * Moist Air Volume
     */
    v;
    /**
     * Degree of Saturation
     */
    s;
    /**
     * Standard Atmospheric Air Pressure
     */
    atm;
    /**
     * Maximum Humidity Ratio
     */
    hrMax;
    /**
     * Initialize a new psychrometric state.
     */
    constructor(state, options) {
        this.state = state;
        this.options = options;
        Psychrolib.SetUnitSystem(options.unitSystem === 'IP' ? Psychrolib.IP : Psychrolib.SI);
        this.atm = Psychrolib.GetStandardAtmPressure(options.altitude);
        this.hrMax = Psychrolib.GetHumRatioFromTDewPoint(options.dpMax, this.atm);
        this.db = state.db;
        switch (state.measurement) {
            case ('dbrh'): {
                this.rh = state.other;
                [this.hr, this.wb, this.dp, this.vp, this.h, this.v, this.s] = Psychrolib.CalcPsychrometricsFromRelHum(state.db, state.other, this.atm);
                break;
            }
            case ('dbwb'): {
                this.wb = state.other;
                [this.hr, this.dp, this.rh, this.vp, this.h, this.v, this.s] = Psychrolib.CalcPsychrometricsFromTWetBulb(state.db, state.other, this.atm);
                break;
            }
            case ('dbdp'): {
                this.dp = state.other;
                [this.hr, this.wb, this.rh, this.vp, this.h, this.v, this.s] = Psychrolib.CalcPsychrometricsFromTDewPoint(state.db, state.other, this.atm);
                break;
            }
            case ('dbhr'): {
                this.dp = Psychrolib.GetTDewPointFromHumRatio(state.db, state.other, this.atm);
                [this.hr, this.wb, this.rh, this.vp, this.h, this.v, this.s] = Psychrolib.CalcPsychrometricsFromTDewPoint(state.db, this.dp, this.atm);
                if (!SMath.approx(this.hr, state.other) && Math.abs(SMath.error(this.hr, state.other)) > PsyState.TOL) {
                    throw new Error(`Error in psychrolib computation. Expected "${state.other}" but found "${this.hr}" for ${state.measurement}.`);
                }
                break;
            }
            case ('dbh'): {
                this.hr = Psychrolib.GetHumRatioFromEnthalpyAndTDryBulb(state.other, state.db);
                this.dp = Psychrolib.GetTDewPointFromHumRatio(state.db, this.hr, this.atm);
                [this.hr, this.wb, this.rh, this.vp, this.h, this.v, this.s] = Psychrolib.CalcPsychrometricsFromTDewPoint(state.db, this.dp, this.atm);
                if (!SMath.approx(this.h, state.other) && Math.abs(SMath.error(this.h, state.other)) > PsyState.TOL) {
                    throw new Error(`Error in psychrolib computation. Expected "${state.other}" but found "${this.h}" for ${state.measurement}.`);
                }
                break;
            }
            default: {
                throw new Error(`Invalid measurement type ${state.measurement}.`);
            }
        }
    }
    /**
     * Convert this psychrometric state to an X-Y coordinate on a psychrometric chart.
     */
    toXY() {
        // Determine if additional padding is needed to show axis names
        const fontPad = this.options.showAxisNames ? (1.5 * this.options.font.size) : 0;
        // The lower-left location
        const origin = {
            x: this.options.padding.x + (this.options.flipXY ? fontPad : 0),
            y: this.options.padding.y + (this.options.flipXY ? fontPad : 0),
        };
        // The upper-right location
        const bound = {
            x: this.options.size.x - this.options.padding.x - (this.options.flipXY ? 0 : fontPad),
            y: this.options.size.y - this.options.padding.y - (this.options.flipXY ? 0 : fontPad),
        };
        if (this.options.flipXY) {
            return {
                x: SMath.clamp(SMath.translate(this.hr, 0, this.hrMax, origin.x, bound.x), origin.x, bound.x),
                y: SMath.clamp(SMath.translate(this.db, this.options.dbMin, this.options.dbMax, bound.y, origin.y), origin.y, bound.y)
            };
        }
        else {
            return {
                x: SMath.clamp(SMath.translate(this.db, this.options.dbMin, this.options.dbMax, origin.x, bound.x), origin.x, bound.x),
                y: SMath.clamp(SMath.translate(this.hr, 0, this.hrMax, bound.y, origin.y), origin.y, bound.y)
            };
        }
    }
    /**
     * Calculate the dry bulb temperature of dry air with enthalpy `h`
     */
    static getDryBulbWithEnthalpy(h) {
        return Psychrolib.GetTDryBulbFromEnthalpyAndHumRatio(h, 0);
    }
}