By pass factor of the cooling coil = 0.2

The return air from the room is mixed with the outside air before entry to the cooling coil in the ratio of 3:1 by mass If 20 $m^3/min$ of fresh air is supplied find:

i) Condition of air leaving the coil,

ii) Capacity of cooling coil in TR,

iii) Room sensible heat factor.

Mumbai University > Mechanical Engineering > Sem 8 > Refrigeration and air conditioning

Marks: 14M

Year: May 2016

Locate point 'a' $40^o$C DBT and 50% RH and point 'b' $26^o$C and 50% RH and point 'd' $10^o$C and saturated condition on psychrometric chart. then locate the point 'c' in such a way

$ac/bc=3/1$

join c and d then locate point 'e' in such a way that

$de/dc=0.2$

i)condition of air leaving the coil is @'e' from chart it is $14.5^o$C and 88% RH. ii)Capacity of cooling coil in TR:

mass of air passing through room

$m_a$=fresh air supplied/specific volume of dry air @ e

=20/0.823= 0.405 kg/sec

Cooling load on coil: $ m_a (h_c-h_d)/3.5$ =0.405(63.5-29.5)/3.5

=3.934 ton

iii) Room sensible heatfactor: the condition 'e' represents the condition of air leaving the conditioner coil and entering into the hall and comes out at condition 'b' after taking the load in the hall. there fore 'eb' line represents the SHR line of the air conditioning space. now from chart

SHR=0.71