Help Needed: Modeling a Loop Heat Pipe System for Mars Mission

[stevemclaren]

hey guys,

im trying to model a loop heat pipe (lhp) system to cool various things on a spacecraft mission to Mars for a project I am doing in uni, does anyone know any equations that i could use to compute a value for length of lhp etc?? I've found lots of journals on the internet giving example performances, so many kW for a certain amount of lhp using ammonia for instance, but can't find anywhere that gives equations or steps to calculating these numbers.

i know the idea on here is to have a go first but i can't seem to get anything. hope this is ok, please take pity!

cheers

 

[BigJDubs]

!The length of a loop heat pipe (LHP) is determined by the design parameters of the system, such as the thermal load, the working fluid, the conductor diameter, and the heat transfer coefficients. There are several equations that you can use to calculate the length of an LHP. For example, the following equation is used to calculate the length of an LHP using R134a as the working fluid: L=((2*Q*A)/(ρ*μ*g*F*(T_s-T_e)))^(1/4)where Q is the thermal load, A is the cross sectional area of the heat pipe, ρ is the density of the working fluid, μ is the viscosity of the working fluid, g is the acceleration due to gravity, F is the fin efficiency, T_s is the saturation temperature of the working fluid, and T_e is the temperature of the evaporator. You can also use the following equation to calculate the length of an LHP using ammonia as the working fluid: L=((2*Q*A)/(φ*μ*g*F*(T_s-T_e)))^(1/4)where φ is the volumetric heat capacity of the working fluid. You can find more information about LHP design and equations in various textbooks and research papers.