# m278hlair: Minenergo-278. Heat losses of overhead pipeline segment In pipenostics: Diagnostics, Reliability and Predictive Maintenance of Pipeline Systems

## Description

Calculate values of heat flux emitted by overhead pipeline segment (surrounded by air) 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.

## Usage

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16``` ```m278hlair( 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 = 26, 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 overhead laying this is the ambient temperature. 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]. `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 overhead laying this is the thermal conductivity of open air. Type: `assert_double`. `len` length of pipeline segment, [m]. Type: `assert_double`. `duration` duration of heat flux emittance, [hour]. Type: `assert_double`.

## Details

Details on using `k1` and `k2` are the same as for `m278hlcha`.

## 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`.

Other Minenergo: `m278hlcha()`, `m278hlund()`, `m278insdata`, `m278inshcm()`, `m278soildata`, `m325beta()`, `m325dropt()`, `m325nhldata`, `m325nhl()`, `m325testbench`
 ```1 2``` ``` m278hlair() #  138.7736 ```