ASHRAE Journal - February 2013 - 24

300
4 Port
Valve

Refrigerant: Ammonia
Orifice Diameter: 2 mm
250 Length: 12 mm
Condensing: 45°C

Condenser

Compressor

200
Two Phase P&O
Formula TP

Evaporator

150

100

Oil
Separator
Low
Pressure
Receiver

Single Phase
P&O Formula SP
Orifice Devices

50

0
1.0 0.8 0.6 0.4 0.2 0.0
Dry
Dryness
0 5 10 15 20 25 30
Wet
Subcooling (K)

Simplified Ammonia LPR System
With Orifice Expansion Devices

Figure 4: Mass flow vs. refrigerant condition and simplified LPR system.
Figure 4 shows the calculated mass flow of ammonia
through an orifice 0.08 in. (2 mm) in diameter and 0.5 in. (12
mm) in length when condensing temperature is 113°F (45°C)
under varying inlet conditions from dry saturated to 45°F (25
K) subcooled. It can be seen that mass flow is very dependent on inlet condition, indicating that the proposed method of
control is feasible.
A further advantage of the simplified system is that refrigerant charge is even further reduced because the liquid line
between the condenser and heat exchanger is drained.

Conclusions

2013

IIAR

INDUSTRIAL REFRIGERA
TION

&

MARCH 17–20 • THE BROADMOOR • COLORADO SPRINGS, CO

www.info.hotims.com/44629-29
With more than 1,000 refrigeration professionals in attendance, the
IIAR Industrial Refrigeration Conference & Exhibition is the largest event
dedicated exclusively to industrial refrigeration held anywhere in the world.

Featuring NEW CO2 Program! • Visit

www.IIAR.org for more details

The International Institute of Ammonia Refrigeration promotes advocacy, education, information
and industry standards for the safe and efficient use of ammonia and other natural refrigerants.

There would appear to be an opportunity to replace R-22
systems in certain applications with well-tried low-charge ammonia systems that could be fully automatic and even more
efficient than the systems being replaced. The best alternative
refrigerant, apart from ammonia, would appear to be R-410A
(Table 1). However, it has a much lower critical temperature,
which means it cannot match efficiencies achieved by ammonia systems.

References
1. Pearson S.F. 1982/83. “Refrigerating systems using low pressure
receivers.” Proc. Inst. Ref. 79.
2. Pearson S.F. 1995/96. “Ammonia low pressure receivers.” Proc.
Inst. Ref. 93.
3. Cotter D. 2010. Improvement of Heat Transfer Performance of
an Ammonia Cooler. Ph.D. Thesis, London South Bank University.
4. Pearson, A. 2012. “Ammonia.” ASHRAE/NIST Refrigerants
Conference, p.12.
5. Payne W.V et al. 2004. “A mass flow-rate correlation for refrig.,
erants and refrigerant mixtures flowing through short tubes.” HVACR
Research Journal 10(1).
February 2013

Used with permission of IIAR

Mass Flow (kg/h)

fluctuate about the level of
the upper orifice, producing
a level control effect. The
mass flow of vapor passing
through the upper orifice
will be negligible compared
to the combined mass flow
of liquid.
Payne and O’Neal5 carried
out experiments on mass flow
of several refrigerants through
short tube orifices in 2004 and
produced empirical formulae
that matched the data.
Sandy Small of Glasgow
used their empirical equations to estimate orifice
performance of the environment-friendly
refrigerants
R-717 (ammonia), R-152a,
R-1234ze (E), R-1234yf,
R-290 (propane) and R-747
(carbon dioxide).



ASHRAE Journal - February 2013

Table of Contents for the Digital Edition of ASHRAE Journal - February 2013

Contents
Commentary
Industry News
Letters
Meetings and Shows
Feature Articles
R-22 Hard Act to Follow: Ammonia Low-Pressure Receiver Systems
Long-Term Commercial GSHP Performance: Part 7: Achieving Quality
Thermally Active Floors: Part 2: Design
Future of DCV for Commercial Kitchens
Standing Columns and Special Sections
Building Sciences
Emerging Technologies
ACREX India 2013 Show Guide
Refrigeration Applications
InfoCenter
Data Centers
IAQ Applications
Special Products
Classified Advertising
Advertisers Index
ASHRAE Journal - February 2013 - Intro
ASHRAE Journal - February 2013 - Cover1
ASHRAE Journal - February 2013 - Cover2
ASHRAE Journal - February 2013 - 1
ASHRAE Journal - February 2013 - 2
ASHRAE Journal - February 2013 - Contents
ASHRAE Journal - February 2013 - Commentary
ASHRAE Journal - February 2013 - 5
ASHRAE Journal - February 2013 - Industry News
ASHRAE Journal - February 2013 - 7
ASHRAE Journal - February 2013 - 8
ASHRAE Journal - February 2013 - 9
ASHRAE Journal - February 2013 - 10
ASHRAE Journal - February 2013 - 11
ASHRAE Journal - February 2013 - Letters
ASHRAE Journal - February 2013 - 13
ASHRAE Journal - February 2013 - Meetings and Shows
ASHRAE Journal - February 2013 - 15
ASHRAE Journal - February 2013 - R-22 Hard Act to Follow: Ammonia Low-Pressure Receiver Systems
ASHRAE Journal - February 2013 - 17
ASHRAE Journal - February 2013 - 18
ASHRAE Journal - February 2013 - 19
ASHRAE Journal - February 2013 - 20
ASHRAE Journal - February 2013 - 21
ASHRAE Journal - February 2013 - 22
ASHRAE Journal - February 2013 - 23
ASHRAE Journal - February 2013 - 24
ASHRAE Journal - February 2013 - 25
ASHRAE Journal - February 2013 - Long-Term Commercial GSHP Performance: Part 7: Achieving Quality
ASHRAE Journal - February 2013 - 27
ASHRAE Journal - February 2013 - 28
ASHRAE Journal - February 2013 - 29
ASHRAE Journal - February 2013 - 30
ASHRAE Journal - February 2013 - 31
ASHRAE Journal - February 2013 - 32
ASHRAE Journal - February 2013 - 33
ASHRAE Journal - February 2013 - 34
ASHRAE Journal - February 2013 - 35
ASHRAE Journal - February 2013 - Thermally Active Floors: Part 2: Design
ASHRAE Journal - February 2013 - 37
ASHRAE Journal - February 2013 - 38
ASHRAE Journal - February 2013 - 39
ASHRAE Journal - February 2013 - 40
ASHRAE Journal - February 2013 - 41
ASHRAE Journal - February 2013 - 42
ASHRAE Journal - February 2013 - 43
ASHRAE Journal - February 2013 - 44
ASHRAE Journal - February 2013 - 45
ASHRAE Journal - February 2013 - 46
ASHRAE Journal - February 2013 - 47
ASHRAE Journal - February 2013 - Future of DCV for Commercial Kitchens
ASHRAE Journal - February 2013 - 49
ASHRAE Journal - February 2013 - 50
ASHRAE Journal - February 2013 - 51
ASHRAE Journal - February 2013 - 52
ASHRAE Journal - February 2013 - 53
ASHRAE Journal - February 2013 - 54
ASHRAE Journal - February 2013 - 55
ASHRAE Journal - February 2013 - Building Sciences
ASHRAE Journal - February 2013 - 57
ASHRAE Journal - February 2013 - 58
ASHRAE Journal - February 2013 - 59
ASHRAE Journal - February 2013 - 60
ASHRAE Journal - February 2013 - 61
ASHRAE Journal - February 2013 - 62
ASHRAE Journal - February 2013 - Emerging Technologies
ASHRAE Journal - February 2013 - 64
ASHRAE Journal - February 2013 - ACREX India 2013 Show Guide
ASHRAE Journal - February 2013 - 64b
ASHRAE Journal - February 2013 - S1
ASHRAE Journal - February 2013 - S2
ASHRAE Journal - February 2013 - S3
ASHRAE Journal - February 2013 - S4
ASHRAE Journal - February 2013 - S5
ASHRAE Journal - February 2013 - S6
ASHRAE Journal - February 2013 - S7
ASHRAE Journal - February 2013 - S8
ASHRAE Journal - February 2013 - S9
ASHRAE Journal - February 2013 - S10
ASHRAE Journal - February 2013 - S11
ASHRAE Journal - February 2013 - S12
ASHRAE Journal - February 2013 - S13
ASHRAE Journal - February 2013 - S14
ASHRAE Journal - February 2013 - S15
ASHRAE Journal - February 2013 - S16
ASHRAE Journal - February 2013 - S17
ASHRAE Journal - February 2013 - S18
ASHRAE Journal - February 2013 - S19
ASHRAE Journal - February 2013 - S20
ASHRAE Journal - February 2013 - S21
ASHRAE Journal - February 2013 - S22
ASHRAE Journal - February 2013 - Refrigeration Applications
ASHRAE Journal - February 2013 - InfoCenter
ASHRAE Journal - February 2013 - 67
ASHRAE Journal - February 2013 - 68
ASHRAE Journal - February 2013 - 69
ASHRAE Journal - February 2013 - 70
ASHRAE Journal - February 2013 - 71
ASHRAE Journal - February 2013 - Data Centers
ASHRAE Journal - February 2013 - 73
ASHRAE Journal - February 2013 - 74
ASHRAE Journal - February 2013 - IAQ Applications
ASHRAE Journal - February 2013 - 76
ASHRAE Journal - February 2013 - 77
ASHRAE Journal - February 2013 - Special Products
ASHRAE Journal - February 2013 - Classified Advertising
ASHRAE Journal - February 2013 - Advertisers Index
ASHRAE Journal - February 2013 - Cover3
ASHRAE Journal - February 2013 - Cover4
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