Nomenclature

c empirical tower constant

C_pw constant specific heat of water

C_r heat capacity ratio

C_s derivative of saturated air enthalpy with respect to temperature

e effectiveness

e_p roughness of pipe

h_boiler boiler efficiency

h_eng engine efficiency

h_motor motor efficiency

h_pump pump efficiency

h_WH fraction of waste heat that can be recovered from the gas engine driven chiller

f friction factor

g gravitational constant

gpm_cnd volume flow rate of cooling water through condenser

gpm_evp volume flow rate of chilled water through evaporator

h_a enthalpy of moist air per mass of dry air

h_s enthalpy of saturated air

h_s,w enthalpy of saturated air at water conditions

H_cnd dynamic head loss due to condenser water flow

H_piping head loss in pipe and fittings

H_tower required static head due to tower lift

L_eq total equivalent length of all piping, valves, fittings, and strainers

LMTD log mean temperature difference

load  cooling load (tons)

m mass flow rate

Ntu number of overall transfer units

P_pump pumping power

P_motor required input power of pump motor

Q heat transfer rate

Q_gas heat input to engine of gas engine driven chiller

Q_gas,cred amount of heat that can be recovered from gas engine driven chiller

Q_WH waste heat rejected from engine of gas engine driven chiller

Re_d Reynolds number calculated using pipe diameter

s velocity of water through condenser tubes

T temperature

TDH total dynamic head

T_cnd,in temperature of cooling water entering condenser

T_db outdoor dry bulb temperature

T_evp,out temperature of chilled water exiting evaporator

UA overall conductance

V volume

V_T total volume

W work

Additional subscripts:

act actual

Carnot based on Carnot efficiency

cmp compressor

cnd condenser

CT cooling tower

evp evaporator

frict friction

i inlet condition

o exit condition

w water

WH waste heat