1. The problem statement, all variables and given/known data Hello everyone, I hope that you guys could lend me a hand. I need to calculate the heat loss at any point over a long pipe while considering lambda of the pipe. I am trying to use octave to find a reasonable flow-rate to keep the temperature loss to a minimum at a reasonable pressure. lambda= 0.02 inner radius=0.1m outer radius=0.2m Distance=4000m initial inside temperature 100C outside temperature=10C Assumptions: laminar flow. no vertical variations. 2. Relevant equations 3. The attempt at a solution %Heat loss long distance transfer %Initial Settings PipeRadiusInside=0.1; PipeRadiusOutside=0.2; TotalPipeDistance=1000; Time=1; PipeSegmentLength=16; OutsideTemperature=10; InsulatingCapacity=0.020; Temperature=; CurrentTemperature=100; i=0; %% PipeThickness=PipeRadiusOutside-PipeRadiusInside; Resistance=((PipeThickness*log(PipeRadiusOutside/PipeRadiusInside))/InsulatingCapacity); U=1/Resistance; TemperatureDifference=CurrentTemperature-OutsideTemperature; SegmentVolume=2*pi*PipeSegmentLength; EnergyOfWater=4.2*TemperatureDifference*SegmentVolume*0.9982; while i<TotalPipeDistance/Time i=i+PipeSegmentLength; Temperature=[Temperature CurrentTemperature]; HeatLoss=2*pi*PipeRadiusOutside*U*TemperatureDifference*PipeSegmentLength; EnergyOfWater=EnergyOfWater-HeatLoss; CurrentTemperature=((EnergyOfWater-HeatLoss)/(4.2*SegmentVolume*0.9982))+OutsideTemperature; TemperatureDifference=CurrentTemperature-OutsideTemperature; end plot(Temperature) It gives me results which look like the could be right as it reacts to changes in variables correctly but it is definitely incorrect. Also I do not know how to relate it to flow rate. I really need help and would be thankful for an example. Thank you for your time.