Calculate values of heat flux emitted by pipeline segment mounted in channel as a function of construction, operation, and technical condition specifications according to Appendix 5.1 of Minenergo Method 278.

This type of calculations is usually made on design stage of district heating network (where water is a heat carrier) and is closely related to building codes and regulations.

m278hlcha(
  t1 = 110,
  t2 = 60,
  t0 = 5,
  insd1 = 0.1,
  insd2 = insd1,
  d1 = 0.25,
  d2 = d1,
  lambda1 = 0.09,
  lambda2 = 0.07,
  k1 = 1,
  k2 = k1,
  lambda0 = 1.74,
  z = 2,
  b = 0.5,
  h = 0.5,
  len = 1,
  duration = 1
)

Arguments

t1

temperature of heat carrier (water) inside the supplying pipe, [°C]. Type: assert_double.

t2

temperature of heat carrier (water) inside the returning pipe, [°C]. Type: assert_double.

t0

temperature of environment, [°C]. In case of channel laying this is the temperature of subsoil. Type: assert_double.

insd1

thickness of the insulator which covers the supplying pipe, [m]. Type: assert_double.

insd2

thickness of the insulator which covers the returning pipe, [m]. Type: assert_double.

d1

external diameter of supplying pipe, [m]. Type: assert_double.

d2

external diameter of returning pipe, [m]. Type: assert_double.

lambda1

thermal conductivity of insulator which covers the supplying pipe [W/m/°C]. Type: assert_double.

lambda2

thermal conductivity of insulator which covers the returning pipe [W/m/°C]. Type: assert_double.

k1

technical condition factor for insulator of supplying pipe, []. Type: assert_double.

k2

technical condition factor for insulator of returning pipe, []. Type: assert_double.

lambda0

thermal conductivity of environment, [W/m/°C]. In case of channel laying this is the thermal conductivity of subsoil. Type: assert_double.

z

channel laying depth, [m]. Type: assert_double.

b

channel width, [m]. Type: assert_double.

h

channel height, [m]. Type: assert_double.

len

length of pipeline segment, [m]. Type: assert_double.

duration

duration of heat flux emittance, [hour]. Type: assert_double.

Value

Heat flux emitted by pipeline segment during duration, [kcal]. If len of pipeline segment is 1 m and duration of heat flux emittance is set to 1 hour then the return value is equal to that in [kcal/m/h] units and so comparable with values of heat flux listed in Minenergo Order 325. Type: assert_double.

Details

k1 and k2 factor values equal to one mean the best technical condition of insulation of appropriate pipes, whereas for poor technical state factor values tends to five or more.

Nevertheless, when k1 and k2 both equal to one the calculated heat flux [kcal/m/h] is sometimes higher than that listed in Minenergo Order 325. One should consider that situation when choosing method for heat loss calculations.

Examples

 m278hlcha()
#> [1] 86.92977
 #

 ## Naive way to find out technical state (factors k1 and k2) for pipe
 ## segments constructed in 1980:
   optim(
     par = c(1.5, 1.5),
     fn = function(x) {
     # functional to optimize
       abs(
           m278hlcha(k1 = x[1], k2 = x[2]) -
           m325nhl(year = 1980, laying = "channel", d = 250, temperature = 110)
       )
     },
     method = "L-BFGS-B",
     lower = 1.01, upper = 4.4
   )$par
#> [1] 4.285442 4.323628
   # [1] 4.285442 4.323628