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 whilst 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.
Refrigeration – inside the box
This CPD article takes us back to the principles upon which
the majority of refrigeration equipment used in building
services is based. It looks inside the box that normally sits
on the roof or in a plant room
T
oday, where energy efficiency of all Vapour Compression Theory four basic components: low temperature heat
systems and plant is vital in reducing The vapour compression refrigeration cycle exchanger (evaporator); compressor; high
carbon emissions, it can be a useful is based on the reverse Carnot cycle. The temperature heat exchanger (condenser); and
tool to understand how equipment cycle transfers heat energy from a low to a a turbine (replaced by a pressure reducing
functions. Refrigeration has often been high temperature level and earns the name device in practice).
regarded as a necessary evil and many of its 'Thermal Pump'. Figure 1 illustrates the cycle Figure 2 shows the processes on a
system characteristics a mystery. CIBSE has components involved. The cycle requires temperature/entropy diagram where the >
produced the Knowledge series of publications,
which provides overviews and applications
Cooling Method Usage in Efficiency Capital Carbon
of many topics including refrigeration. The
Building Cost Footprint
publications concentrate on application rather
Services
than theory.
In this article a brief section shows the basis
Vapour Compression 333 333 3 33
of the refrigeration cycle, with references to Absorption – generated heat 3 3 333 333
further reading for additional study. Absorption – waste/free heat
3 333 333 3
The vapour compression, or mechanical
Air Cycle 3 3 333 33
refrigeration system is the most common
Evaporative 33 333 3 3
method of cooling in air conditioning, but
it is worth realising that there is a number
Dessicant 33 3 333 3
of different cycles or systems that produce
Carbon Dioxide 3 33 333 3
cooling. Table 1 is a subjective comparison –
3 Low 33 Average 333 High
for further reading go to the CIBSE Guides
B2 and B4. Table 1: Cooling Methods
www.cibsejournal.com March 2009 CIBSE Journal 61
CIBSEmar09 pp61-64 cpd.indd 61 4/3/09 14:51:45
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