Lecture Objectives:

1
Lecture Objectives

• Analysis of Absorption Cooling Cycles

2
Carnot Cycles

• COPvapor_compressionQcooling/Pelectric
  COPmaxTcooling/(Tenviromnet-Tcooling)
  
• COPabsorptionQcooling/Qheating COPmax
  Tcooling/(Tenviromnet-Tcooling)
  (Theat_source-T environment)/ Theat_source
• 
  COPmax_absorption COP vapor compression x
  Correction for VC cycle

3
Absorption cooling with preheater(system
improvement 1)
Rich ammonia vapor
4
5
Refrigeration and air conditioning (Ramesh et al)
4
Absorption cooling with preheater
Saturated vapor at p1
1V3
Major heat source
6
1
mixing
isotherm
6h
1
Useful cooling energy
1L 2
4
5
1
Saturated liquid at p1
2 , 2
Saturated liquid at p1
1
Cooling tower
Pumping energy
COP Q cooling / Q heating (Pump ???)
5
For Real energy analysis you need real h-x
diagram!
hfg for H2O
hfg for NH3
6
Use of precooling(system improvement 2)
7
Absorption cooling with precooling
Saturated vapor at p1
1V3
Major heat source
6
6
1
6h
mixing
Saturated liquid at p1
isotherm
1
Useful cooling energy (larger!)
1L 2
4
1
Saturated liquid at p1
2 , 2
4
5
1
Cooling tower (needs to cool more!)
Pumping energy
8
System improvement 3
Generator with of Enrichment NH3
Different
8V
8L
9
10
8LLP
11
9
Heat rejection with separation into liquid and
vapor (Enrichment NH3 in the vapor mixture)
This is our point
cooling
1
42V
Separator
65V
Q12 /m1
cooling
Q45 /m4
x8
m8
8
7
m1
m2
5
2
mixture
sub cooled liquid
isotherm
m3
2L
Q12
x8
x1
10
Ammonia Enrichment Process(rectification)
11
Absorption system with Enrichment (no preheater
nor precooler)
Saturated vapor at p2
3V
8V
mixing
3
11
8L
1
Useful cooling energy
8LLP
10
2
3L
9
Saturated liquid at p2
Saturated liquid at p1
1
12
Example of H2O-NH3 System

• Text Book (Thermal Environmental Engineering)
  Example 5.5
• HW 1
• Solve the problem 5.6 from the textbook
  (LiBr-H2O)
• Beside example 5.6, you will need to study
  example 5.6 and 5.7
• Due date February 25th.

13
LiBr-H2O Systems
14
LiBr-H2O Systems
15
Twine vessel LiBr-H2O Systems
16
Useful information about LiBr absorption chiller

• http//www.cibse.org/content/documents/Groups/CHP/
  Datasheet20720-20Absorption20Cooling.pdf
• Practical Tips for Implementation of absorption
  chillers
• Identify and resolve any pre-existing problems
  with a cooling system, heat rejection system,
  water treatment etc, before installing an
  absorption chiller, or it may be unfairly blamed.
  
• Select an absorption chiller for full load
  operation (by the incorporation of thermal stores
  if necessary) as COP will drop by up to 33 at
  part-load.
• Consider VSD control of absorbent pump to improve
  the COP at low load.
• Consider access and floor-loading (typical 2 MW
  Double-effect steam chiller 12.5 tons empty, 16.7
  tones operating).
• Ensure ambient of temperature of at least 5C in
  chiller room to prevent crystallization.
• http//www.climatewell.com/index.html/application
  s/solar-cooling

17
System with no pump(Platen-Munter system)

• H2O-NH3 hydrogen

http//www.youtube.com/watch?v34K61ECbGD4