R/HeatT_function.R

In joshuakrobertson/R-Package_ReVuePro: ReVuePro: Enabling analysis of thermal images captured by FLIRs VuePro R

#' ReVuePro: HeatT
#'
#' A function to calculate total dry heat transfer (convective and radiative) from a surface with known surface area.
#' @details Note that conductive heat transfer is not yet included in total heat transfer calculations, and wind assumed to be absent.
#' @param Ts A vector or single value pertaining to the surface temperature of the object in question (that from which heat is being transfered), in degrees Celsius.
#' @param Ta A vector or single value pertaining to the ambient temperature experienced by the object in question (agian, that from which heat is being transfered), in degrees Celsius.
#' @param atm The atmospheric pressure at the time that surface temperature measurements were drawn in kiloPascals. Default is 101.325.
#' @param dim The length of the object from which surface temperature measurements were drawn, in the orientation of airflow, in metres. Default is the diameter of a circle with the surface area defined by SA.
#' @param SA The surface area of the object from which surface temperature measurments were drawn, in metres squared.
#' @param Emis The emissivity of the object from which surface temperature measurments were drawn. Default is 0.95.
#' @param par A logical parameter that defines whether heat transfer calculation are to be conducted by parallel processing. Default is false.

#' @keywords VuePro, Thermal
#' @import doParallel bigleaf dplyr Thermimage
#' @examples
#' my_data = read.csv("C:/ThermDat/Surface_Temp.csv")
#' horizontal_dim = 0.15
#' SA_circle = pi*(0.15/2)^2
#' HeatT(Ts = c(my_data$SurfaceT), Ta = 21, atm = 100.1, dim = horizontal_dim, SA = SA_circle, Emis = 0.98, par = "T")
#' @export

HeatT = function(Ts,Ta,atm = 101.325, dim = 2*sqrt(SA/pi), SA, Emis = 0.95, par = "FALSE"){

  par = as.logical(par)

  if (is.numeric(Ts) == FALSE){
    return ("Ts must be a numeric vector or value.")
  }
  if (is.numeric(Ta) == FALSE){
    return ("Ta must be a numeric vector or value.")
  }
  if (is.numeric(dim) == FALSE){
    return ("dim must be a numeric value equal to the horizontal length of the object, in m.")
  }
  if (is.numeric(SA) == FALSE){
    return ("SA must be numeric value equal to the surface area of the object in m2.")
  }

  require('bigleaf')
  require('dplyr')
  require('Thermimage')

  if (par == TRUE){
     require('doParallel')
  } else if (par != "T" | par != "F"){
    return ("par must be T or F.")
  }

  if (length(Ta) != length(Ts)){
    if (length(Ta) != 1){
      return("Ta must be of length 1, or equal to the length of Ts")
    } else if (length(Ta) == 1){
      Ta = c(rep(Ta, length(Ts)))
    }
  }

   TD = data.frame(Ta = Ta, Ts = Ts, ID = seq(from = 1, to = length(Ts), by = 1))

   NAs_TR = TD[c(which(is.na(Ts))),]
   CTD = na.omit(TD)

    Kt = c()
    Vis = c()
    Alpha = c()
    Gr = c()
    Nu = c()
    Hc = c()

if (par == FALSE){
  for (i in 1:length(CTD$Ta)) {
    Kt[i] = airtconductivity(CTD$Ta[i])
    Vis[i] = kinematic.viscosity(CTD$Ta[i], atm)
    Alpha[i] = 1 / (CTD$Ta[i] + 273.15)
  }

  for (i in 1:length(CTD$Ts)) {
    Gr[i] = ((Alpha[i]) * (9.81) * (dim)^3 *
      (CTD$Ts[i] - CTD$Ta[i])) / (Vis[i])^2
  }

  for (i in 1:length(CTD$Ts)) {
    Nu[i] = sign(Gr[i]) * 0.50 * (abs(Gr[i]))^0.25
  }

  for (i in 1:length(CTD$Ts)) {
    Hc[i] = Nu[i] * (Kt[i] / dim)
  }

  Qconv = c()
  Qrad = c()

  for (i in 1:length(CTD$Ts)) {
    Qconv[i] = SA * (Hc[i]) * (CTD$Ts[i] - CTD$Ta[i])
    Qrad[i] = SA * (5.67 * 10^-8) * Emis^2*
      ((CTD$Ts[i] + 273.15)^4 - (CTD$Ta[i] + 273.15)^4)
  }

  Qtot = c()

  for (i in 1:length(CTD$Ts)) {
    Qtot[i] = Qconv[i] + Qrad[i]
  }

  CTD$Qtot = Qtot
  NAs_TR$Qtot = NA

  to_return = rbind(CTD, NAs_TR)
  to_return = dplyr::arrange(to_return, ID)

 return(to_return$Qtot)

} else if (par == TRUE){
  foreach(i=1:length(CTD$Ta)) %dopar% {
    Kt[i] = airtconductivity(CTD$Ta[i])
    Vis[i] = kinematic.viscosity(CTD$Ta[i], atm)
    Alpha[i] = 1 / (CTD$Ta[i] + 273.15)
  }

  foreach(i=1:length(CTD$Ts)) %dopar% {
    Gr[i] = ((Alpha[i]) * (9.81) * (dim)^3 *
      (CTD$Ts[i] - CTD$Ta[i])) / (Vis[i])^2
  }

  foreach(i=1:length(CTD$Ts)) %dopar% {
    Nu[i] = sign(Gr[i]) * 0.50 * (abs(Gr[i]))^0.25
  }

  foreach(i=1:length(CTD$Ts)) %dopar% {
    Hc[i] = Nu[i] * (Kt[i] / dim)
  }

  Qconv = c()
  Qrad = c()

  foreach(i=1:length(CTD$Ts)) %dopar% {
    Qconv[i] = SA * (Hc[i]) * (CTD$Ts[i] - CTD$Ta[i])
    Qrad[i] = SA * (5.67 * 10^-8) * Emis^2*
      ((CTD$Ts[i] + 273.15)^4 - (CTD$Ta[i] + 273.15)^4)
  }

  Qtot = c()

  foreach(i=1:length(CTD$Ts)) %dopar% {
    Qtot[i] = Qconv[i] + Qrad[i]
  }

  CTD$Qtot = Qtot
  NAs_TR$Qtot = NA

  to_return = rbind(CTD, NAs_TR)
  to_return = dplyr::arrange(to_return, ID)

 return(to_return$Qtot)
}
}