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Performance analysis of cooling tower using desiccant

  • Bhavna Mishra
  • Aalekh Srivastava
  • Laxmikant YadavEmail author
Original

Abstract

Cooling towers are one of the biggest heat and mass transfer devices that are in widespread use. In this work, the cooling tower model has been fabricated and silica gel mesh (SGM) column is installed at the inlet of the cooling tower. Experiments have been performed for three different modes namely with 0, 1 and 2 silica gel mesh with the subcases of varying air velocity and inlet water temperature. Experimental results demonstrated that the addition of a desiccant column (SGM) at inlet improves the range and effectiveness of the cooling tower. At higher inlet temperature (80°C and 4.3 m/s air velocity) the range of 2 SGM cooling tower is 2°C greater than without SGM cooling tower. This study also analyzes the effect of SGM column on the cooling water flow rate of the condenser of the thermal power plant and it has been found that required mass flow rate of SGM cooling tower is less than the normal cooling tower at any operating conditions. The minimum value of cooling water flow rate (32.05 kg/s) is achieved when inlet water temperature and velocity are 50°C and 3 m/s, respectively. Further, the maximum reduction in cooling water flow rate is 18.22% using two SGM column at 4 m/s velocity and 50°C inlet temperature. Hence, this modification helps improve the cooling capacity and reduce the water consumption of the cooling tower.

Nomenclature

Symbol Description Units

wr

Resultant uncertainty -

mg

Mass flow rate of gas kg/s

ml

Mass flow rate of liquid water in cooling tower kg/s

TG2

Temperature of air at the exit of cooling tower °C

TG1

Temperature of air at the inlet of cooling tower °C

TL2

Temperature of water at the outlet of cooling tower °C

TL1

Temperature of water at the inlet of cooling tower °C

∆Tmax

Maximum possible temperature difference in shell and tube heat exchanger °C

\( {Y}_2^{\prime } \)

Humidity ratio of air at the exit of cooling tower kg/kg

\( {Y}_1^{\prime } \)

Humidity ratio of air at the inlet of cooling tower kg/kg

Ysat

Humidity ratio at the saturated condition kg/kg

H2

Enthalpy of air at the exit of cooling tower kJ/kg

H1

Enthalpy of air at the inlet of cooling tower kJ/kg

HL1

Enthalpy of water at the inlet of cooling tower kJ/kg

HL2

Enthalpy of water at the exit of cooling tower kJ/kg

cwl

Specific heat of liquid water kJ/kg K

cpg

Specific heat of the air kJ/kg K

∆Hvap

Enthalpy of vapourization kJ/kg

ky

Mass transfer coefficient kg/m2s

a

Perimeter of control volume dz m

hc

Convective heat transfer coefficient W/m2K

\( {\dot{m}}_{cw} \)

Mass flow rate of cooling water consumed in the condenser kg/s

Htg

Height of enthalpy gas transfer unit m

Ntg

Number of enthalpy gas transfer unit –

z

Height of packing section m

Hsat

Enthalpy of air at the saturated condition kJ/kg

\( {\dot{m}}_s \)

Mass flow rate of steam in the condenser kg/s

As

Surface area of desiccant m2

Notes

Compliance with ethical standards

Conflict of interest

On behalf of all authors, the corresponding author states that there is no conflict of interest.

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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Department of Mechanical EngineeringMMMUTGorakhpurIndia
  2. 2.Department of Mechanical EngineeringNIT HamirpurHamirpurIndia

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