Buildings.Fluid.DataCenters.Racks.Liquid.Examples

Collection of models that illustrate model use and test models

Information

This package contains examples for the use of models that can be found in Buildings.Fluid.DataCenters.Racks.

Extends from Modelica.Icons.ExamplesPackage (Icon for packages containing runnable examples).

Package Content

Name	Description
ColdPlateR_P	Example model for cold plate

Buildings.Fluid.DataCenters.Racks.Liquid.Examples.ColdPlateR_P

Example model for cold plate

Buildings.Fluid.DataCenters.Racks.Liquid.Examples.ColdPlateR_P

Information

Example model of a cold plate with different GPU utilization.

The GPU utilization is modeled as a pulse that is parameterized based on the data of Patel et al. (2024), Figure 6(b) which is for the Llama2-50B LLM, neglecting the very high frequency and approximating the change in utilization with a periodic pulse input. The cold plate operates at a constant flow rate at the start of the simulation. The flow rate then ramps down to half the design value to show the change in case temperature.

References

Pratyush Patel, Esha Choukse, Chaojie Zhang, Íñigo Goiri, Brijesh Warrier, Nithish Mahalingam, and Ricardo Bianchini.
Characterizing Power Management Opportunities for LLMs in the Cloud.
In Proceedings of the 29th ACM International Conference on Architectural Support for Programming Languages and Operating Systems, Volume 3 (ASPLOS '24).
Association for Computing Machinery, New York, NY, USA, 207–222. 2024.
doi:10.1145/3620666.3651329.

Extends from Modelica.Icons.Example (Icon for runnable examples).

Parameters

Type	Name	Default	Description
HeatFlowRate	P_nominal	2*66000	Design heat flow rate at u=1, also called Thermal Design Power (TDP) [W]
TemperatureDifference	dT_nominal	7	Design temperature difference of coolant fluid [K]
SpecificHeatCapacity	cp_default	Medium.specificHeatCapacityC...	Heat capacity, to compute additional dry mass [J/(kg.K)]
OCP_1kW_OAM_PG25	dat	dat(PIT_nominal=P_nominal, m...	Performance data

Modelica definition

model ColdPlateR_P "Example model for cold plate" extends Modelica.Icons.Example; package Medium = Buildings.Media.Antifreeze.PropyleneGlycolWater( T_default=303.15, property_T=303.15, X_a=0.25) "Propylene glycol"; parameter Modelica.Units.SI.HeatFlowRate P_nominal=2*66000 "Design heat flow rate at u=1, also called Thermal Design Power (TDP)"; parameter Modelica.Units.SI.TemperatureDifference dT_nominal = 7 "Design temperature difference of coolant fluid"; final parameter Modelica.Units.SI.MassFlowRate m_flow_nominal=P_nominal/ dT_nominal/cp_default "Nominal mass flow rate at TDP"; parameter Modelica.Units.SI.SpecificHeatCapacity cp_default= Medium.specificHeatCapacityCp(state=state_default) "Heat capacity, to compute additional dry mass"; parameter Data.OCP_1kW_OAM_PG25 dat(PIT_nominal=P_nominal, m_flow_nominal=m_flow_nominal) "Performance data"; Buildings.Controls.OBC.CDL.Reals.Sources.Pulse uti( amplitude=0.4, width=2/5, period=5, shift=0.2, offset=0.62) "Utilization of hardware"; Buildings.Controls.OBC.CDL.Reals.Sources.Ramp m_flow( height=-m_flow_nominal/2, duration=5, offset=m_flow_nominal, startTime=30) "Mass flow rate"; Buildings.Fluid.DataCenters.Racks.Liquid.ColdPlateR_P rac( redeclare package Medium = Medium, dat=dat, energyDynamics=Modelica.Fluid.Types.Dynamics.FixedInitial) "Rack with cold plate heat exchangers"; Buildings.Fluid.Sources.MassFlowSource_T sou( redeclare package Medium = Medium, use_m_flow_in=true, nPorts=1) "Mass flow source"; Buildings.Fluid.Sources.Boundary_pT bou( redeclare package Medium = Medium, nPorts=1) "Pressure boundary condition"; Fluid.Sensors.TemperatureTwoPort senTOut( redeclare package Medium = Medium, allowFlowReversal=false, m_flow_nominal=m_flow_nominal, tau=0) "Outlet temperature"; Modelica.Blocks.Math.Gain PIT( k(final unit="W", min=0) = dat.PIT_nominal, u(final unit="1"), y(final unit="W")) "Power consumption by the IT equipment"; protected parameter Medium.ThermodynamicState state_default = Medium.setState_pTX( T=Medium.T_default, p=Medium.p_default, X=Medium.X_default[1:Medium.nXi]) "Medium state at default values"; equation connect(sou.ports[1],rac. port_a); connect(m_flow.y, sou.m_flow_in); connect(rac.port_b, senTOut.port_a); connect(senTOut.port_b, bou.ports[1]); connect(uti.y, PIT.u); connect(PIT.y, rac.P); end ColdPlateR_P;