Transient heat transfer in heat exchangers

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SUMMARY

The discussion focuses on transient heat transfer in heat exchangers, specifically for an engine generating 140 kW of thermal heat. The user presents a transient equation to model the cooling process involving water flow through a radiator and a heat exchanger with air. Key parameters include a water mass flow rate of 0.37 m³/s and specific heat capacity of 4.1855 J/(g·K). The user seeks assistance in solving the equation and determining the area of the heat exchanger, highlighting the need for additional information regarding hot air temperature and engine temperature.

PREREQUISITES
  • Understanding of transient heat transfer principles
  • Familiarity with heat exchanger design
  • Knowledge of thermodynamic properties of fluids
  • Proficiency in solving differential equations related to thermal systems
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Engineers, thermal system designers, and researchers involved in heat exchanger design and thermal management of engines will benefit from this discussion.

firavia
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Considering an engine generating thermal heat at 140 kw and when the generation starts the thermal equilibrium of the engine will be distrubed , a radiator is installed to cool the engine this radiator cool the engine through flow of water and water is cooled inside a heat exchanger with air .
I set a transient equation to my system but I am still unable to solve it please check my equation if it is correct and if there is anything missing .

Qgen+mdot.cp water.(Tentring water - T exiting water)=\rhoC .V . dTengine/dt
P.S:ignoring radiation trasfer.
Qgen = 140 kw .
mdot water=0.37m3/s.
cpwater=4.1855 J/(g·K)
C cast iron=0.46
Rho=7870KG/m3.
v=>volume=0.01m3.
Initial conditions:
at t=0sec Tengine = 45 Deg Twater entring = 30 deg c
How can I design a radiator for such system , after solving the equation I still have 2 unknowns Thot air and T2 engine .
From the above how can I identify the area of my heat exchanger ?
 
Last edited:
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Pleas I would like to know where I am wrong
 
Nobody want to help me ?!
 

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