US 5,732,560 AGranted

System and method for performing cooling

AssigneeSvenska Rotor Maskiner AB

InventorsErik Thuresson, Henrik Ohman

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Abstract

The invention relates to a refrigeration system of the air cycle cooling system type, also called reversed Brayton cycle in which the air flow through compressor means (12, 16), heat exchanger means (24) for withdrawal of heat from the compressed air and finally expander means (22) from where it is delivered to perform cooling. According to the invention the system includes heat load means (41) having a large flow resistance, creating a considerable over-pressure at the expander outlet (23). A rotary screw machine is included in the expander (22) and also in the compressor means (12, 16), which latter screw rotor machine (12) is driven solely by the screw rotor machine (22) of said expander means. A screw rotor machine (16) connected in parallel with the screw rotor machine (12) of said compressor means is driven separately, preferably by a drive engine (19), the rotational speed of which si controlled by pressure sensing means (36) in a conduit between the expander outlet (23) and an inlet to the heat load means (41), and thereby--via said expander means--also drive the velocity of the screw rotor machine (12) of said compressor means. The system is particularly intended for cooling the electronic equipment in air-craft when being on the ground.

Claims36

Dependent claims

System for performing cooling including

first conduit means (10) connected to air of substantially atmospheric pressure,
compressor means (12, 16) having inlet means (11, 15) connected to said first conduit means (10) for compressing said air,
second conduit means (20) connected to outlet means (13, 17) of said compressor means (12, 16),
expander means (22) having inlet means (21) connected to said second conduit means (20) for expanding said air, said expander means (22) including at least one rotary screw machine,
third conduit means (30) connected to outlet means (23) of said expander means (22),
heat load means (41) having inlet means (31) connected to said third conduit means (30) and outlet means (42) connected to substantially atmospheric pressure,
and main heat exchanger means (24) in heat exchanging relation with said compressed air, anywhere between said inlet means (11, 15) of said compressor means (12, 16) and said outlet means (23) of said expander means (22), said main heat exchanger means (24) withdrawing heat from said air,
said third conduit means (30) and said heat load means (41) having a flow resistance creating a pressure drop between said expander outlet means (23) and the outlet means (42) of said heat load means (41), characterized in that said compressor means (12, 16) includes more screw rotor machines than said expander means (22), which screw rotor machines of said compressor means (12, 16) are in parallel arrangement and have a larger internal volume ratio than each rotary screw machine of said expander means (22), and that at least a pair of screw rotor machines comprising a screw rotor machine (12) of said compressor means and a screw rotor machine (22) of said expander means have a constant relation between their rotational speeds established by a drive interconnection (14), which is the only one to activate the screw rotor machine (12) of said compressor means, in addition to which at least one of the screw rotor machines (16) of said compressor means is drivingly separated from said expander means (22).

5 more elements

A method for performing cooling by

compressing air of substantially atmospheric pressure,
expanding said compressed air in at least one rotary screw machine (22),
cooling said air after the compression has started but before the expansion has ended,
delivering said expanded air to heat load means (41),
cooling said heat load means (41) with said delivered air and
venting said air from said heat load means (41) to substantially atmospheric pressure.
thereby establishing an air flow, said delivering and said cooling of said heat load means (41) creating a pressure drop in said air flow, characterized by the measures of using more rotary screw machines for said compressing than are used for said expanding, arranging said rotary screw machines used for said compressing in parallel, using rotary screw machines of larger internal volume ratio for said compressing than for said expanding and having at least a pair of screw rotor machines comprising a screw rotor machine (12) of said compressor means and a screw rotor machine (22) of said expander means to run with a constant relation between their rotational speeds by a drive interconnection (14) being the only one influencing the screw rotor machine (12) of said compressor means, in addition to which at least one of the screw rotor machines (16) of said compressor means being drivingly separated from said expander means (22).

4 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/836,656Filed 16 May 1997
Priority: SE 940396617 Nov 1994
Granted: 31 Mar 1998
Term ends: Not estimatedThe source records don’t support an estimate.

Classification15 codes

F04C 28/02
Control of, monitoring of, or safety arrangements for, pumps or pumping installations specially adapted for elastic fluids: specially adapted for…
B64D 13/06
Arrangements or adaptations of air-treatment apparatus for aircraft crew or passengers, or freight space: the air being conditioned
F04C 23/003
Of similar working principle: having complementary function
F04C 28/08
Control of, monitoring of, or safety arrangements for, pumps or pumping installations specially adapted for elastic fluids: characterised by…