# Massively trace forwards thermal-hydraulic regime for district heating network

Source:`R/tracefw.R`

`tracefw.Rd`

Trace values of thermal-hydraulic regime (temperature, pressure,
flow rate, and other) in the bunched pipeline along the flow direction using
user-provided values of *specific heat loss power*.

## Usage

```
tracefw(
sender = c(0, 1),
acceptor = c(1, 2),
temperature = c(70, NA_real_),
pressure = c(pipenostics::mpa_kgf(6), NA_real_),
flow_rate = c(20, NA_real_),
d = rep_len(100, 2),
len = rep_len(72.446, 2),
loss = rep_len(78.4, 2),
roughness = rep_len(0.001, 2),
inlet = c(0.5, 1),
outlet = c(1, 1),
elev_tol = 0.1,
method = "romeo",
verbose = TRUE,
csv = FALSE,
file = "tracefw.csv",
use_cluster = FALSE
)
```

## Arguments

- sender
identifier of the node which heat carrier flows out. Type: any type that can be painlessly coerced to character by

`as.character`

.- acceptor
identifier of the node which heat carrier flows in. According to topology of test bench considered this identifier should be unique for every row. Type: any type that can be painlessly coerced to character by

`as.character`

.- temperature
Sensor-measured temperature of heat carrier (water) sensor-measured on the root node, [

*°C*]. Use`NA_float_`

s for nodes without temperature sensor. Type:`assert_double`

.- pressure
Sensor-measured absolute pressure of heat carrier (water) inside the pipe on the root node, [

*MPa*]. Use`NA_float_`

s for nodes without pressure sensor. Type:`assert_double`

.- flow_rate
Sensor-measured amount of heat carrier (water) on root node that is transferred by pipe during a period, [

*ton/hour*]. Type:`assert_double`

. Use`NA_float_`

s for nodes without flow rate sensor.- d
internal diameter of pipe (i.e.diameter of acceptor's incoming edge), [

*mm*]. Type:`assert_double`

.- len
pipe length (i.e. length of acceptor's incoming edge), [

*m*]. Type:`assert_double`

.- loss
user-provided value of

*specific heat loss*power for each pipe in tracing path, [*kcal/m/h*]. Values of the argument can be obtained experimentally, or taken from regulatory documents. Type:`assert_double`

.- roughness
roughness of internal wall of pipe (i.e. acceptor's incoming edge), [

*m*]. Type:`assert_double`

.- inlet
elevation of pipe inlet, [

*m*]. Type:`assert_double`

.- outlet
elevation of pipe outlet, [

*m*]. Type:`assert_double`

.- elev_tol
maximum allowed discrepancy between adjacent outlet and inlet elevations of two subsequent pipes in the traced path, [

*m*]. Type:`assert_number`

.- method
method of determining

*Darcy friction factor*:`romeo`

`vatankhan`

`buzelli`

Type:

`assert_choice`

. For more details see`dropp`

.- verbose
logical indicator: should they watch tracing process on console? Type:

`assert_flag`

.- csv
logical indicator: should they incrementally dump results to

*csv*- file while tracing? Type:`assert_flag`

.- file
name of

*csv*-file which they dump results to. Type:`assert_character`

of length 1 that can be used safely to create a file and write to it.- use_cluster
utilize functionality of parallel processing on multi-core CPU. Type:

`assert_flag`

.

## Value

`data.frame`

containing results (detailed log) of tracing in

`node`

*Tracing job*. Identifier of the node which regime parameters is calculated for. Values in this vector are identical to those in argument`acceptor`

. Type:`assert_character`

.`tracing`

*Tracing job*. Identifiers of nodes from which regime parameters are traced for the given node. Identifier`sensor`

is used when values of regime parameters for the node are sensor readings. Type:`assert_character`

.`backward`

*Tracing job*. Identifier of tracing direction. It constantly equals to`FALSE`

. Type:`assert_logical`

.`aggregation`

*Tracing job*. Identifier of the aggregation method associated with traced values. For forward tracing the only option is`identity`

. Type:`assert_character`

.`temperature`

*Traced thermal hydraulic regime*. Traced temperature of heat carrier (water) that is associated with the node, [*°C*]. Type:`assert_double`

.`pressure`

*Traced thermal hydraulic regime*. Traced pressure of heat carrier (water) that is associated with the node, [*MPa*]. Type:`assert_double`

.`flow_rate`

*Traced thermal hydraulic regime*. Traced flow rate of heat carrier (water) that is associated with the node, [*ton/hour*]. Type:`assert_double`

.`job`

*Tracing job*. Value of tracing job counter. For forward tracing value of`job`

counts the number of traced paths from root node. Type:`assert_count`

.

Type: `assert_data_frame`

.

## Details

They consider the topology of district heating network represented by
`m325testbench`

:

Tracing starts from sensor-equipped root node and goes forward, i.e along
the flow direction. Function `traceline`

serves under the
hood for tracing identified linear segments from root node to every
terminal node. Hence they only need root node to be equipped with sensors.
Sensors at other nodes are redundant in forward tracing, since the tracing
algorithm by no means consider them for tracing.

Moreover in the forward tracing algorithm they assume the flow of heat carrier is distributed proportionally to the cross-sectional area of the outgoing pipeline. Actually, a lot of reasons may cause significant deviations from this assumption. As a result, the sequence of paired backward/forward tracing may be divergent for regime parameters.

Though some input arguments are natively vectorized their individual values
all relate to common part of district heating network, i.e. associated with
common object. It is due to isomorphism between vector representation and
directed graph of this network. For more details of isomorphic topology
description see `m325testbench`

.

They are welcome to couple the algorithm with functionality of data.table.

## See also

Other Regime tracing:
`m325tracebw()`

,
`m325tracefw()`

,
`m325traceline()`

,
`tracebw()`

,
`traceline()`

## Examples

```
library(pipenostics)
# Minimum two nodes should be in district heating network graph:
tracefw(verbose = FALSE)
#> node tracing backward aggregation loss flux Q temperature
#> 1 1 sensor FALSE identity NA NA NA 70.00000
#> 2 2 1 FALSE identity 78.4 279.0696 136314.4 69.71603
#> pressure flow_rate job
#> 1 0.5883990 20 0
#> 2 0.5813153 20 1
# Consider isomorphic representation of District Heating Network graph:
DHN <- pipenostics::m325testbench
# * remove irrelevant parameters from the test bench
DHN[c("year", "insulation", "laying", "beta", "exp5k")] <- NULL
DHN[c("temperature", "pressure", "flow_rate")] <- NA_real_
# * avoid using numeric identifiers for nodes:
DHN$sender <- sprintf("N%02i", DHN$sender)
DHN$acceptor <- sprintf("N%02i", DHN$acceptor)
# * alter units:
DHN$d <- 1e3 * DHN$d # convert [m] to [mm]
# * provide current regime parameters for root node
root_node <- 12
DHN[root_node, "temperature"] <- 70.4942576978 # [°C]
DHN[root_node, "pressure"] <- 0.6135602014 # [MPa]
DHN[root_node, "flow_rate"] <- 274.0 # [ton/hour]
# * provide actual values of specific heat loss power, [kcal/m/h], for each
# segment N01 - N26. Since N12 is a root node, the specific heat loss
# power for this acceptor is set to 0 (or may be any other numeric value).
actual_loss <- c(
96.8, 96.8, 71.2, 116.7, 71.3, 96.8, 78.5, 116.7, 28.6, 24.5,
116.7, 0.0, 153.2, 96.8, 96.8, 116.7, 24.5, 116.7, 28.6, 96.8,
78.5, 116.7, 71.3, 96.8, 96.8, 71.1
)
# Trace the test bench forward for the first time:
fw_report <- do.call(
"tracefw", c(as.list(DHN), list(loss = actual_loss), verbose = FALSE, elev_tol = .5)
)
```