After air and water mixing, the process of gas compression in the downcomer shaft or pipe of a hydraulic air compressor is considered nearly isothermal due to (i) the mass flow rate of water being typically of three orders higher than that of the gas it compresses, (ii) water having a heat capacity approximately four times that of air, and (iii) the intimate contact and large heat transfer area between the gas phase and the liquid phase of the bubbly flow. A formulation for estimation of the efficiency of a closed- or open-loop hydraulic air compressor, expressed in terms of the principal hydraulic air compressor design variables, is presented. The influence of a hitherto underappreciated factor affecting the performance of these installations, such as the solubility of the gas being compressed in the water, is explored. A procedure for estimating the yield of compressed gas, accounting for these solubility losses, is explained and used to determine the mechanical efficiency of historical hydraulic air compressor installations from reported performance data. The result is a significant downward revision of hydraulic air compressor efficiency by approximately 20% points in comparison to most reported efficiencies. However, through manipulation of cosolute concentrations in the water, and the temperature of the water (through regulation of the ejection of compression heat), the mechanical efficiency can be increased to the formerly reported levels. The thermo-economic implication of these efficiency determinations is that in a modern context, hydraulic air compressors may be able to outperform conventional mechanical gas compression equipment.

References

References
1.
Millar
,
D.
,
2014
, “
A Review of the Case for Modern-Day Adoption of Hydraulic Air Compressors
,”
Appl. Therm. Eng.
,
69
(
1–2
), pp.
55
77
.
2.
Bidini
,
G.
,
Grimaldi
,
C. N.
, and
Postrioti
,
L.
,
1999
, “
Performance Analysis of a Hydraulic Air Compressor
,”
Proc. Inst. Mech. Eng. Part A
,
213
(
A3
), pp.
191
203
.
3.
Rice
,
W.
,
1976
, “
Performance of Hydraulic Gas Compressor
,”
ASME J. Fluids Eng.
,
98
(4), pp.
645
652
.
4.
Nishi
,
A.
,
1996
, “
Highly Efficient Gas Turbine System Using Isothermal Compression
,”
JSME Int. J. Ser. B, Fluids Therm. Eng.
,
39
(
3
), pp.
615
620
.
5.
McPherson
,
M. J.
,
1993
,
Subsurface Ventilation and Environmental Engineering
,
Chapman & Hall
,
London, UK
.
6.
Rogers
,
G. F. C.
, and
Mayhew
,
Y. R.
,
1967
,
Engineering Thermodynamics: Work and Heat Transfer
,
Longman
,
London, UK
.
7.
E. B. W.
,
1910
, “
Report on Oxygen Content of Hydraulic Air Compressor at Ragged Chutes
,”
Mines Miner.
,
31
(
3
), pp.
129
131
.
8.
Pavese
,
V.
,
2015
, “
Energy and Exergy Analysis of a Hydraulic Air Compressor for Application in the Mining Industry
,” M.S. thesis, Politecnico di Torino, Torino, Italy.
9.
Schulze Leroy
,
E.
,
1954
,
Hydraulic Air Compressors
,
U.S. Department of Interior
,
Washington, DC
.
10.
Langborne
,
P. L.
,
1979
, “
Hydraulic Air Compression: Old Invention—New Energy Source
,”
Chart. Mech. Eng.
,
26
(
10
), pp.
76
81
.
11.
Peele
,
P.
,
1930
,
Compressed Air Plant
,
5th ed.
,
Wiley
,
New York
.
12.
Anonymous
,
1950
, “
Charles Havelock Taylor (Obituary)
,”
Can. Min. Metall. Bull.
,
56
, pp.
191
203
.
13.
Bernstein
,
P.
,
1910
, “
Hydraulic Compressors
,”
Z. Ver. Dtsch. Ing.
,
54
(
45
), pp.
1903
1908
(in German).
14.
Hartenberg
,
R. S.
, and
Denavit
,
J.
,
1960
, “
The Fabulous Air Compressor
,”
Mach. Des.
,
32
(
15
), pp.
168
170
.
15.
Auclair
,
A.
,
1957
, “
Ragged Chutes
,”
Can. Min. J.
,
78
(
8
), pp.
98
101
.
16.
Taylor
,
C. H.
,
1910
, “
Cobalt Hydraulic Air Compressor
,”
Mines Miner.
,
30
(
9
), pp.
532
534
.
17.
Markman
,
B. G.
,
1928
, “
The Hydraulic Compressor Station at the Falue Mine
,”
Jernkontorets Ann.
,
10
, pp.
497
517
.
18.
Kotas
,
T. J.
,
1985
,
The Exergy Method of Thermal Plant Analysis
,
Butterworths
,
London, UK
.
19.
Szargut
,
J.
,
Morris
,
D. R.
, and
Steward
,
F. R.
,
1988
,
Exergy Analysis of Thermal, Chemical and Metallurgical Processes
,
Hemisphere
,
New York
.
20.
Szargut
,
J.
,
2005
,
Exergy Method: Technical and Ecological Applications
,
WIT Press
,
Boston, MA
.
21.
Glueckauf
,
E.
,
1951
, “
The Composition of Atmospheric Air
,”
T. F.
Malone
, ed.,
Compendium of Meteorology
,
American Meteorological Society
,
Boston, MA
, pp.
3
10
.
22.
Tans
,
P.
, and
Keeling
,
R.
,
2014
, “
Trends in Carbon Dioxide: Global CO2 Data 2013
,” Earth System Research Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO, accessed Oct. 21, 2014, http://www.esrl.noaa.gov/gmd/ccgg/trends/global.html#global_data
You do not currently have access to this content.