Calcolatore Forza di Resistenza
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Heat Transfer Rate
250.80 kW
Heat Transfer Rate vs Mass Flow Rate
Formula
Heat Exchanger Energy Balance
The heat transfer rate is determined by the fluid properties and temperature change.
Formula
Q = m_dot cp delta_T
where m_dot is the mass flow rate, cp is the specific heat capacity, and delta_T is the temperature change of the fluid. This applies to each fluid stream independently; at steady state, the heat lost by the hot stream equals the heat gained by the cold stream (minus losses).
Esempio Risolto
Water at 2 kg/s cooled from 80 deg C to 50 deg C.
- 01delta_T = 80 - 50 = 30 deg C
- 02Q = 2 x 4.18 x 30 = 250.8 kW
- 03This is the heat that must be transferred to the cooling medium.
Domande Frequenti
What types of heat exchangers exist?
Shell-and-tube (most common in industry), plate-and-frame (compact, high efficiency), finned-tube (air-cooled), double-pipe (simple, small duties), and spiral (fouling resistance). Selection depends on duty, pressures, and fouling.
What is LMTD?
Log Mean Temperature Difference is the effective driving force for heat transfer: LMTD = (delta_T1 - delta_T2) / ln(delta_T1 / delta_T2). It is used to size the heat exchanger area: Q = U A LMTD, where U is the overall heat transfer coefficient.
What is specific heat for common fluids?
Water: 4.18 kJ/(kg-K). Air: 1.005. Ethylene glycol (50%): 3.35. Thermal oil: 1.7-2.3. Steam: 2.01 (at 100 deg C, 1 atm). Refrigerant R134a liquid: 1.43.
Impara