Add radiators (#18728)

* Add radiators

* Limit heat transfer to fluid heat capacity

* Adjust datafield names

* Fix material arbitrage

* This code has been debugged, and so there are no more bugs. Debugging code is therefore unnecessary

* Adjust radiator layer subfloor visibility

* Cache CVars

* No default

Co-authored-by: metalgearsloth <31366439+metalgearsloth@users.noreply.github.com>

* Like and unsubscribe

* Fix CVar caching

---------

Co-authored-by: metalgearsloth <31366439+metalgearsloth@users.noreply.github.com>

Content.Server/Atmos/Components/HeatExchangerComponent.cs

@@ -0,0 +1,36 @@
+namespace Content.Server.Atmos.Components;
+
+[RegisterComponent]
+public sealed class HeatExchangerComponent : Component
+{
+    [ViewVariables(VVAccess.ReadWrite)]
+    [DataField("inlet")]
+    public string InletName { get; set; } = "inlet";
+
+    [ViewVariables(VVAccess.ReadWrite)]
+    [DataField("outlet")]
+    public string OutletName { get; set; } = "outlet";
+
+    /// <summary>
+    /// Pipe conductivity (mols/kPa/sec).
+    /// </summary>
+    [ViewVariables(VVAccess.ReadWrite)]
+    [DataField("conductivity")]
+    public float G { get; set; } = 1f;
+
+    /// <summary>
+    /// Thermal convection coefficient (J/degK/sec).
+    /// </summary>
+    [ViewVariables(VVAccess.ReadWrite)]
+    [DataField("convectionCoefficient")]
+    public float K { get; set; } = 8000f;
+
+    /// <summary>
+    /// Thermal radiation coefficient. Number of "effective" tiles this
+    /// radiator radiates compared to superconductivity tile losses.
+    /// </summary>
+    [ViewVariables(VVAccess.ReadWrite)]
+    [DataField("radiationCoefficient")]
+    public float alpha { get; set; } = 400f;
+}
+

Content.Server/Atmos/EntitySystems/AtmosphereSystem.Gases.cs

@@ -78,6 +78,16 @@ namespace Content.Server.Atmos.EntitySystems
             return mixture.Temperature * cachedHeatCapacity;
         }
 
+        /// <summary>
+        ///     Add 'dQ' Joules of energy into 'mixture'.
+        /// </summary>
+        public void AddHeat(GasMixture mixture, float dQ)
+        {
+            var c = GetHeatCapacity(mixture);
+            float dT = dQ / c;
+            mixture.Temperature += dT;
+        }
+
         /// <summary>
         ///     Merges the <see cref="giver"/> gas mixture into the <see cref="receiver"/> gas mixture.
         ///     The <see cref="giver"/> gas mixture is not modified by this method.

Content.Server/Atmos/EntitySystems/HeatExchangerSystem.cs

@@ -0,0 +1,97 @@
+using Content.Server.Atmos.EntitySystems;
+using Content.Server.Atmos.Piping.Components;
+using Content.Server.Atmos.Piping.Unary.Components;
+using Content.Server.Atmos;
+using Content.Server.Atmos.Components;
+using Content.Server.NodeContainer.EntitySystems;
+using Content.Server.NodeContainer.Nodes;
+using Content.Server.NodeContainer;
+using Content.Shared.Atmos.Piping;
+using Content.Shared.Atmos;
+using Content.Shared.CCVar;
+using Content.Shared.Interaction;
+using JetBrains.Annotations;
+using Robust.Shared.Configuration;
+using Robust.Shared.Timing;
+
+namespace Content.Server.Atmos.EntitySystems;
+
+public sealed class HeatExchangerSystem : EntitySystem
+{
+    [Dependency] private readonly AtmosphereSystem _atmosphereSystem = default!;
+    [Dependency] private readonly IConfigurationManager _cfg = default!;
+    [Dependency] private readonly NodeContainerSystem _nodeContainer = default!;
+
+    float tileLoss;
+
+    public override void Initialize()
+    {
+        base.Initialize();
+        SubscribeLocalEvent<HeatExchangerComponent, AtmosDeviceUpdateEvent>(OnAtmosUpdate);
+
+        // Getting CVars is expensive, don't do it every tick
+        _cfg.OnValueChanged(CCVars.SuperconductionTileLoss, CacheTileLoss, true);
+    }
+
+    public override void Shutdown()
+    {
+        base.Shutdown();
+        _cfg.UnsubValueChanged(CCVars.SuperconductionTileLoss, CacheTileLoss);
+    }
+
+    private void CacheTileLoss(float val)
+    {
+        tileLoss = val;
+    }
+
+    private void OnAtmosUpdate(EntityUid uid, HeatExchangerComponent comp, AtmosDeviceUpdateEvent args)
+    {
+        if (!EntityManager.TryGetComponent(uid, out NodeContainerComponent? nodeContainer)
+                || !_nodeContainer.TryGetNode(nodeContainer, comp.InletName, out PipeNode? inlet)
+                || !_nodeContainer.TryGetNode(nodeContainer, comp.OutletName, out PipeNode? outlet))
+        {
+            return;
+        }
+
+        // Positive dN flows from inlet to outlet
+        var dt = 1/_atmosphereSystem.AtmosTickRate;
+        var dP = inlet.Air.Pressure - outlet.Air.Pressure;
+        var dN = comp.G*dP*dt;
+
+        GasMixture xfer;
+        if (dN > 0)
+            xfer = inlet.Air.Remove(dN);
+        else
+            xfer = outlet.Air.Remove(-dN);
+
+        var radTemp = Atmospherics.TCMB;
+
+        // Convection
+        var environment = _atmosphereSystem.GetContainingMixture(uid, true, true);
+        if (environment != null)
+        {
+            radTemp = environment.Temperature;
+
+            // Positive dT is from pipe to surroundings
+            var dT = xfer.Temperature - environment.Temperature;
+            var dE = comp.K * dT * dt;
+            var envLim = Math.Abs(_atmosphereSystem.GetHeatCapacity(environment) * dT * dt);
+            var xferLim = Math.Abs(_atmosphereSystem.GetHeatCapacity(xfer) * dT * dt);
+            var dEactual = Math.Sign(dE) * Math.Min(Math.Abs(dE), Math.Min(envLim, xferLim));
+            _atmosphereSystem.AddHeat(xfer, -dEactual);
+            _atmosphereSystem.AddHeat(environment, dEactual);
+        }
+
+        // Radiation
+        float dTR = xfer.Temperature - radTemp;
+        float a0 = tileLoss / MathF.Pow(Atmospherics.T20C, 4);
+        float dER = comp.alpha * a0 * MathF.Pow(dTR, 4) * dt;
+        _atmosphereSystem.AddHeat(xfer, -dER);
+
+        if (dN > 0)
+            _atmosphereSystem.Merge(outlet.Air, xfer);
+        else
+            _atmosphereSystem.Merge(inlet.Air, xfer);
+
+    }
+}

Content.Shared/CCVar/CCVars.cs

@@ -937,6 +937,12 @@ namespace Content.Shared.CCVar
         public static readonly CVarDef<bool> Superconduction =
             CVarDef.Create("atmos.superconduction", false, CVar.SERVERONLY);
 
+        /// <summary>
+        ///     Heat loss per tile due to radiation at 20 degC, in W.
+        /// </summary>
+        public static readonly CVarDef<float> SuperconductionTileLoss =
+            CVarDef.Create("atmos.superconduction_tile_loss", 30f, CVar.SERVERONLY);
+
         /// <summary>
         ///     Whether excited groups will be processed and created.
         /// </summary>

Resources/Prototypes/Entities/Structures/Piping/Atmospherics/binary.yml

@@ -379,3 +379,45 @@
         acts: ["Destruction"]
   - type: Machine
     board: GasRecyclerMachineCircuitboard
+
+- type: entity
+  parent: GasBinaryBase
+  id: HeatExchanger
+  name: radiator
+  description: Transfers heat between the pipe and its surroundings.
+  placement:
+    mode: SnapgridCenter
+  components:
+  - type: Rotatable
+  - type: Transform
+    noRot: false
+  - type: Sprite
+    sprite: Structures/Piping/Atmospherics/heatexchanger.rsi
+    layers:
+    - sprite: Structures/Piping/Atmospherics/pipe.rsi
+      state: pipeStraight
+      map: [ "enum.PipeVisualLayers.Pipe" ]
+    - state: heStraight
+      map: [ "enum.SubfloorLayers.FirstLayer" ]
+  - type: SubFloorHide
+    visibleLayers:
+    - enum.SubfloorLayers.FirstLayer
+  - type: Appearance
+  - type: PipeColorVisuals
+  - type: AtmosDevice
+  - type: HeatExchanger
+  - type: NodeContainer
+    nodes:
+      inlet:
+        !type:PipeNode
+        nodeGroupID: Pipe
+        pipeDirection: North
+      outlet:
+        !type:PipeNode
+        nodeGroupID: Pipe
+        pipeDirection: South
+  - type: Construction
+    graph: GasBinary
+    node: radiator
+  - type: StaticPrice
+    price: 50

Resources/Prototypes/Recipes/Construction/Graphs/utilities/atmos_binary.yml

@@ -46,6 +46,12 @@
         amount: 2
         doAfter: 1
 
+    - to: radiator
+      steps:
+      - material: Steel
+        amount: 8
+        doAfter: 1
+
   - node: pressurepump
     entity: GasPressurePump
     edges:
@@ -159,3 +165,21 @@
         doAfter: 1
       - tool: Welding
         doAfter: 1
+
+  - node: radiator
+    entity: HeatExchanger
+    edges:
+    - to: start
+      conditions:
+      - !type:EntityAnchored
+        anchored: false
+      completed:
+      - !type:SpawnPrototype
+        prototype: SheetSteel1
+        amount: 8
+      - !type:DeleteEntity
+      steps:
+      - tool: Screwing
+        doAfter: 1
+      - tool: Welding
+        doAfter: 1

Resources/Prototypes/Recipes/Construction/utilities.yml

@@ -663,6 +663,22 @@
   conditions:
     - !type:TileNotBlocked {}
 
+- type: construction
+  id: HeatExchanger
+  name: radiator
+  description: Transfers heat between the pipe and its surroundings.
+  graph: GasBinary
+  startNode: start
+  targetNode: radiator
+  category: construction-category-utilities
+  placementMode: SnapgridCenter
+  canBuildInImpassable: false
+  icon:
+    sprite: Structures/Piping/Atmospherics/heatexchanger.rsi
+    state: heStraight
+  conditions:
+    - !type:TileNotBlocked {}
+
 # ATMOS TRINARY
 - type: construction
   id: GasFilter

Resources/Textures/Structures/Piping/Atmospherics/heatexchanger.rsi/meta.json

@@ -0,0 +1,19 @@
+{
+   "version":1,
+   "size":{
+      "x":32,
+      "y":32
+   },
+   "license":"CC-BY-SA-3.0",
+   "copyright":"Taken from https://github.com/tgstation/tgstation at commit 57cd1d59ca019dd0e7811ac451f295f818e573da and modified by BasedUser",
+   "states":[
+      {
+         "name":"heStraight",
+         "directions":4
+      },
+      {
+         "name":"heBend",
+         "directions":4
+      }
+   ]
+}