tive at some power levels, but are inefficient at
ly aspirated engines. Use blast valves and relief
lower power ranges. Missions requiring very low
valves to protect, and momentarily bypass, the air-
total power may be served by battery-powered
cleaning equipment. Special high-strength intake
systems, which are discussed in paragraph 2-3b.
and exhaust ducting will be needed. Air-shock re-
sistant, hard-mounted supply, and exhaust ducts
b. Parasitic power demand. Open waste-heat re-
are straightforward design problems. Adapt stand-
jection systems using air cooling add substantial
ard commercial high-pressure expansion joint de-
parasitic power loads. The total parasitic load in-
signs to meet the requirements of supply and
cludes coolant circulation pump power; refrigera-
exhaust connections between hard-mounted and
tion (largely compressor) power for facility air cool-
shock-isolated duct segments.
ing; normal radiator or cooling tower fan power;
(3) Choices between hardening techniques and
and booster fan power to overcome the air entrain-
ruggedization of subsystems and components asso-
ment system (AES) air-flow head loss. (AES is dis-
ciated with both air supply and power supply are
cussed in TM 58585. ) Fan power rapidly becomes
delineated in volume five of this technical manual.
the dominant parasitic electrical load at values of
Shock isolation of equipment mentioned herein is
head loss greater than about 5 in. of water. The to-
described in volume four. Remember, this is a total
tal power demand of the power system can be de-
system-engineering approach, all facets integrated.
termined only after the air-flow head loss due to
d. Endurance. Endurance requirements will be
AES blast protection has been established. This re-
a direct function of power profile and subsystem ef-
quires at least a conceptual design for the AES,
ficiency at all profile power levels, which will de-
and that design, in turn, must be based on the
termine the volume of stored fuel and, for cooling
airblast management concepts, primarily for the
tower systems, the volume of stored cooling tower
waste-heat rejection system (chap. 3). An engine
make-up water. These storage volumes strongly af-
combustion air supply and exhaust system should
fect the endurance-dependent design of a facility.
be closely integrated with the waste-heat rejection
Usually, off-peak power operation of a single en-
system, air supply and exhaust.
gine will substantially reduce prime mover efficien-
cy and increase relative fuel and cooling demand
c. Weapon-effect protection. It is important to
per unit electrical power produced. Substantial to-
distinguish between cooling system air demand and
tal power demand reductions are possible if booster
combustion air demand. Cooling-system air re-
fan power in the air-entrainment system can be re-
quirements for evaporation-cooled systems are on
duced at low heat loads by variable speed fan
the order of 50 times greater than the average re-
drives and variable pitch fans, or by cutting out
quirements for combustion air supply and exhaust;
part of a multifan system. Base preliminary esti-
radiator-cooled systems are about 100 times great-
m a t e s of fuel storage requirements on the
er. Consequently, both the physical size of the
weighted average power demand over the total
components and the kinds of components involved
power profile.
make airblast protection for open-cycle, air-cooling
systems an order of magnitude more difficult than
that for combustion air supply and exhaust sys-
2-3. Closed cycle.
tems. Most air-cooling system components will nec-
a. Candidates. Candidates for closed-cycle
essarily be larger and more difficult to harden than
power-supply systems include:
corresponding combustion air system components.
--Battery
(1) For air-cooling systems, the cooling tow-
--Fuel Cell
ers, radiators, and fans are airblast-sensitive com-
--Combined Fuel Cell and Battery Systems
p o n e n t s . In combustion air systems, super-
--Nuclear Reactor
chargers, scavenging blowers, and intake and
--Diesel
exhaust ducting will have limited air shock and
--Stirling
pressure-transient tolerance. For either system,
Except for the battery, none of the closed-cycle
dust separation and filtration equipment, air ducts,
power-supply systems listed have been developed
and particularly flexible duct connections between
to the point where they can be considered as prac-
hard-mounted and shock-isolated equipment will
tical, reliable candidates. Continued research, de-
require special consideration.
velopment, and testing are still required in order
(2) Experiments have shown diesel engines
to transfer the developing systems to practical
themselves to be relatively unaffected by pressure
applications.
transients to several hundreds of psi applied simul-
b. Battery. Except for a paucity of data on me-
taneously to intake and exhaust. Eliminate poten-
chanical shock resistance, battery-powered electri-
tial problems with superchargers by using natural-
2-3
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