CPD Programme
CPD Programme
The CIBSE Journal CPD Programme programme is free and can be used by any
Members of the Chartered Institution of reader. It is organised jointly by CIBSE Journal
Building Services Engineers (CIBSE) and other and London South Bank University, and will
professional bodies are required to maintain help you to meet CIBSE’s requirement for
their professional competence throughout CPD. It will equally assist members of other
their careers. Continuing professional institutions, who should record CPD activities
development (CPD) means the systematic in accordance with their institution’s guidance.
maintenance, improvement and broadening Simply study the module and complete the
of your knowledge and skills, and is therefore questionnaire on the final page, following the
a long-term commitment to enhancing your instructions for its submission. Modules will
competence. CPD is a requirement of both remain available online at www.cibsejournal.
CIBSE and the Register of the Engineering com/cpd while the information they contain
Council (UK). remains current. You can also undertake the
CIBSE Journal is pleased to offer this questionnaire online, and receive your results
module in its CPD programme. The back by return email.
Absorption refrigeration
This article introduces the reader to an alternative cooling cycle to the
familiar vapour compression cycle, in the form of the absorption cycle. The
article will explain the basic principles of the cycle and applications for its
use. In fact, the absorption cooling cycle was invented before the vapour
compression system in the 1850s, but for various reasons, including cost
and low efficiency, did not capture the refrigeration market.
L
ooking at Figure 1, the absorption cycle is
very similar to the vapour compression
Q
out
cycle, in that it uses a circulating
refrigerant, an evaporator, a condenser
and an expansion device. The difference is that
Condenser
the compressor of the vapour compression
cycle is replaced by a chemical absorption
process and generator, with a pump to provide Generator Q
in
the circulation and pressure change.
The vapour compression cycle is described
as a work-operated cycle because it uses a
Expansion Thermal
W
in
valve Compressor
compressor that requires work in the form of Pump
electrical energy to operate. The absorption
cycle is referred to as a heat-operated cycle
Absorber Q
because most of the energy required to operate
out
the cycle is heat energy. This immediately opens
up options for its application and use, over an
Evaporator
electrically driven cooling cycle. Absorption
cooling is worth considering if any of the
following factors apply:
• For a CHP unit where there is spare heat
Q
in
available, or when a new CHP plant is being
considered; > Figure 1 Basic absorption cycle
www.cibsejournal.com November 2009 CIBSE Journal 55
CIBSEnov09 pp55-58 cpd.indd 55 10/22/09 5:18:43 PM
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68