Thermal analysis, pressure drop and exergy loss of energy efficient shell, and triple meshed helical coil tube heat exchanger

ABSTRACT

Majority of studies has been reported in literature in recent years on performance of shell and helical coil tube heat exchanger. The present work attempts to design and analyze experimentally hot water temperature difference, Nusselt number, Dean number, exergy loss, effectiveness and pressure drop in a shell, and triple meshed helical coil tube (TMHCT) heat exchanger. The effects of hot water flowing in TMHCT ranging from 1 to 3 L/min at different inlet temperatures (50°C, 60°C, 70°C, 80°C) and cold water flow in range of 1–3 L/min on shell side at constant inlet temperature 25°C were investigated throughout the experiment. The results show that the heat transfer characteristics increase with increasing hot water volume flow rate and inlet temperature. It was also found that the performance enhancement of shell and TMHCT heat exchanger with least penalty of pressure drop was noticed as compared to existing shell and single helical coil tube heat exchanger.

KEYWORDS:

• Energy efficient
• exergy analysis
• Nusselt number
• pressure drop
• triple meshed helical coil tube

Nomenclatures

A	=	Surface area (m2)
cp,	=	Specific heat (J/kg K)
D	=	Helical coil diameter (m)
E	=	Exergy loss (W)
De	=	Dean number = $Re{\left(\frac{d}{D}\right)}^{0.5}$
d	=	Tube diameter (m)
h	=	Heat transfer coefficient (W/m2k)
H	=	Height (m)
k	=	Thermal conductivity (W/m K)
L	=	Length of tube (m)
n	=	Number of helical coil tube
N	=	Number of helical coil turn
Nu	=	Nusselt number = $\frac{hd}{k}$
P	=	Pitch of helical coil (m)
∆P	=	Pressure drop in TMHCT (Pa)
Q	=	Heat transfer rate (W)
Re	=	Reynolds number = $\frac{4\rho V}{\pi \mu d}$
s	=	Specific entropy (J/kg K)
t	=	Thickness (m)
T	=	Temperature (℃)
ν	=	Velocity of fluid
V	=	Volume flow rate of water (L/min)

Greek Symbols

ρ	=	Density (kg/m3)
µ	=	Viscosity
ε	=	Effectiveness

Subscripts

avg.	=	Average
c	=	Cold
h	=	Hot
i	=	inner
In	=	Inlet
Out	=	Outlet
s	=	Coil tube surface