R/stdVol.R

In sashahafner/biogas: Process Biogas Data and Predict Biogas Production

stdVol <- function(
  vol,
  temp,
  pres,
  rh = 1,
  temp.std = getOption('temp.std', as.numeric(NA)),
  pres.std = getOption('pres.std', as.numeric(NA)),
  unit.temp = getOption('unit.temp', 'C'),
  unit.pres = getOption('unit.pres', 'atm'),
  std.message = TRUE,
  warn = TRUE
) {

  # Check arguments
  checkArgClassValue(vol, c('numeric', 'integer'))
  checkArgClassValue(temp, c('numeric', 'integer'), expected.range = c(0, Inf))
  checkArgClassValue(pres, c('numeric', 'integer'), expected.range = c(0, Inf))
  checkArgClassValue(rh, c('numeric', 'integer'), expected.range = c(0, 1))
  checkArgClassValue(temp.std, c('numeric', 'integer'))
  checkArgClassValue(pres.std, c('numeric', 'integer'), expected.range = c(0, Inf))
  checkArgClassValue(unit.temp, c('character'))
  checkArgClassValue(unit.pres, c('character'))
  checkArgClassValue(std.message, c('logical'))

  # Determine standard conditions if they are omitted
  if(is.na(pres.std)) {
    pres.std <- unitConvert(x = 1, unit = 'atm', to = unit.pres)
  }

  if(is.na(temp.std)) {
    temp.std <- unitConvert(x = 0, unit = 'C', to = unit.temp)
  }


  # Echo standard conditions
  if(std.message) message('Using a standard pressure of ', pres.std, ' ', unit.pres, ' and standard temperature of ', temp.std, ' ', unit.temp, ' for standardizing volume.')

  # Convert pressure to Pa and temp to K
  pres.pa <- unitConvert(x = pres, unit = unit.pres, to = 'Pa')
  temp.k <- unitConvert(x = temp, unit = unit.temp, to = 'K')
  pres.std.pa <- unitConvert(x = pres.std, unit = unit.pres, to = 'Pa')
  temp.std.k <- unitConvert(x = temp.std, unit = unit.temp, to = 'K')

  # Check pres and temp range
  if(warn) {
    if(any(temp.k < 273.15 | temp.k > 373.15)) warning('temp ranges from ', min(na.omit(temp)), ' ', unit.temp, ' to ', max(na.omit(temp)), ' ', unit.temp, '. Is this really correct?')
    if(any(pres.pa < 5E4 | pres.pa > 1.5E5)) warning('pres ranges from ', min(na.omit(pres)), ' ', unit.pres, ' to ', max(na.omit(pres)), ' ', unit.pres, '. Is this really correct?')
  }
 
  # Calculate water vapor pressure in atm (based on NIST)
  pH2O <- rh*watVap(temp.k = temp.k, pres.pa = pres.pa)

  # Correct volume for water and to standard pressure
  vol.dry <- vol*(pres.pa - pH2O)/pres.std.pa

  # Correct dry volume to standard temperature
  vol.std <- vol.dry*temp.std.k/temp.k

  return(vol.std)
}