Method Method Method Method DiscussionDiscussionDiscussionDiscussion Method Method Method Method

DiscussionDiscussionDiscussionDiscussion

Time to reach the specified process pressure of better than 1x10-6 mbar was halved (39 vs. 21 A 12-meter stainless steel coil of 10mm diameter (area = 0.38M2) Chamber volume 0.4M3 Liquid Nitrogen was fed as liquid from a Dewar which included a FET004 Dewar-vessel and control unit

Time to reach the specified process pressure of better than 1x10-6 mbar was halved (39 vs. 21

minutes) by using the cryo-cooler in place of liquid nitrogen control device (FET 004), Dewar-vessel Nitrogen was fed as liquid from a Dewar which included a FET004 Dewar-vessel and control unit controlling pressure between 1.2 – 2 bar. The coil was taken from ambient to a point where the Stratox CryoStratox CryoStratox CryoStratox Cryo----cooler High Efficiency Coolingcooler High Efficiency Coolingcooler High Efficiency Coolingcooler High Efficiency Cooling and control unit. The cool down time was as impressive .

vacuum pressure was 10-6 mbar held for a period of 1 hour from the initiation of pump down the coil was then defrosted under control of the 580 vacuum controller and the system brought back

Replacement of liquid nitrogen and multistage cascade systems across a wide range of applications. Higher

The graph shows that the coil connected to the cryo-cooler cools quicker than LN2 despite being coil was then defrosted under control of the 580 vacuum controller and the system brought back up to atmosphere.

capacity and lower cost than sterling type coolers. The graph shows that the coil connected to the cryo-cooler cools quicker than LN2 despite being

warmer. Cryo-coil operated with LN2. Pressure of 1.5-2 bar is typical for the filling device to have a

Direct comparison with Stratox Cryo-Cooler (2000 Watt cooling capacity @ -100oC) was substi-

• Patent applied for

Zero ODP

warmer. Cryo-coil operated with LN2. Pressure of 1.5-2 bar is typical for the filling device to have a

moderate loss of LN2, regulation by simple switching on and off of the filling device by the hystere-Direct comparison with Stratox Cryo-Cooler (2000 Watt cooling capacity @ -100oC) was substi-tuted for LN2. Connections between the CRYOCOOLER and the cryo-coil were made through

• Zero ODP

Scalable technology - from 1000 W to 100 kW

moderate loss of LN2, regulation by simple switching on and off of the filling device by the hystere-

sis of the sensor. tuted for LN2. Connections between the CRYOCOOLER and the cryo-coil were made through Swagelok compression fittings.

• Scalable technology - from 1000 W to 100 kW

Low capital cost

The system was defrosted using both the rapid defrost capability of the cryo-cooler or the

• Low capital cost

• Oppertional range –193K to 123 K

The curve shows a inconsistent cooling with LN2, which caused a loss of cooling probably as a re-

sult of “bumping” of LN2 in the narrow coil. Tests show the defrost time was reduced from 20 The system was defrosted using both the rapid defrost capability of the cryo-cooler or the FET004 heater ca. 200W, Nitrogen pressure 2 bar to force out the LN2 and heat coil. This gave a complete comparison of process time could be made end of defrost was assumed to be at-

• Oppertional range –193K to 123 K

• Commercially proven in production environments

sult of “bumping” of LN2 in the narrow coil. Tests show the defrost time was reduced from 20

minutes to 3 minutes. To defrost the Meissner trap, the FET 004 control unit uses heated air (heat a complete comparison of process time could be made end of defrost was assumed to be at-mospheric pressure and was plotted against time.

• Commercially proven in production environments

• Capital, energy and installation costs recovered with less than 1 year vs LN2

minutes to 3 minutes. To defrost the Meissner trap, the FET 004 control unit uses heated air (heat

load ca. 200W, pressure 2 bar) to blow out the LN2 and heat up the coil. • Capital, energy and installation costs recovered with less than 1 year vs LN2

• Good qaulity heat (60oC) can be recovered and reused. Good qaulity heat (60oC) can be recovered and reused.

• Safe, low hazard operation. Plotting data from both experiments on the same axes clearly shows the faster cooling and defrost

achieved when using the cryo-cooler. This is probably for two reasons firstly the cryo-cooler deliv-• Temperature control to +/- 2 oC

achieved when using the cryo-cooler. This is probably for two reasons firstly the cryo-cooler deliv-

ers higher mass flows than was possible with liquid nitrogen ers higher mass flows than was possible with liquid nitrogen

The latent heat of evaporation of HF4 (the active cooling principle of a system) is 135.95 kJ/kg (2)

(3) (4) is lower than 198.3 kJ/kg the value for Nitrogen (5). When however the relative boiling points

(Nitrogen 77oK (HF4) 145 oK (2)) are also considered it is clear it is considerably more likely to be (Nitrogen 77oK (HF4) 145 oK (2)) are also considered it is clear it is considerably more likely to be

liquid present in the Cryo-coil when the cryo-cooler is operating than under LN2 and thereby both a liquid present in the Cryo-coil when the cryo-cooler is operating than under LN2 and thereby both a

higher mass and a phase change from liquid to gas help rapidly cool the surface of the Cryo-coil higher mass and a phase change from liquid to gas help rapidly cool the surface of the Cryo-coil

coil. “The Leidenfrost effect is a phenomenon in which a liquid, in near contact with a mass signifi-

cantly hotter than the liquid's boiling point, produces an insulating vapour layer which keeps that liq-

uid from boiling rapidly.” (6) uid from boiling rapidly.” (6)

During defrost the 200 Watts of the in-line heater was significantly less than 4kW of heat (40% of During defrost the 200 Watts of the in-line heater was significantly less than 4kW of heat (40% of

the electrical power consumed) generated by the compressor working on the gas which is directly

injected into the Cryo-coil coil.

Case Study Lower Energy input and Lower cost Case Study Lower Energy input and Lower cost Case Study Lower Energy input and Lower cost Case Study Lower Energy input and Lower cost Case Study Lower Energy input and Lower cost Case Study Lower Energy input and Lower cost Case Study Lower Energy input and Lower cost Case Study Lower Energy input and Lower cost

Cost / Performance Comparison of New Stratox CryoCost / Performance Comparison of New Stratox CryoCost / Performance Comparison of New Stratox CryoCost / Performance Comparison of New Stratox Cryo----cooler vs. LN2 cooler vs. LN2 cooler vs. LN2 cooler vs. LN2 Cost / Performance Comparison of New Stratox CryoCost / Performance Comparison of New Stratox CryoCost / Performance Comparison of New Stratox CryoCost / Performance Comparison of New Stratox Cryo----cooler vs. LN2 cooler vs. LN2 cooler vs. LN2 cooler vs. LN2

Aim Aim Aim Aim To compare cooling and defrost of a Stratox Cryo-cooler against Liquid Nitrogen. The comparison was carried out using a single vacuum system under identical process conditions with no optimi-was carried out using a single vacuum system under identical process conditions with no optimi-sation.

Pfeiffer Vacuum Classic 580 is equipped with a DUO 035 (roughing pump), turbo-molecular pump Pfeiffer Vacuum Classic 580 is equipped with a DUO 035 (roughing pump), turbo-molecular pump TPH 2201 and a Meissner trap for lN2. The volume of the vacuum chamber is 400l. The system is TPH 2201 and a Meissner trap for lN2. The volume of the vacuum chamber is 400l. The system is a typical box coater for optical layers equipped with resistance evaporators, e-gun,

(Ion source, rotating calotte, rear side resistance heater, thickness measurement and PLC-control Stratox Limited, The Office, Mickley, Burley Road , Langham LE15 7JB UK Stratox Limited, The Office, Mickley, Burley Road , Langham LE15 7JB UK Stratox Limited, The Office, Mickley, Burley Road , Langham LE15 7JB UK Stratox Limited, The Office, Mickley, Burley Road , Langham LE15 7JB UK

(Ion source, rotating calotte, rear side resistance heater, thickness measurement and PLC-control system)

Stratox Limited, The Office, Mickley, Burley Road , Langham LE15 7JB UK Stratox Limited, The Office, Mickley, Burley Road , Langham LE15 7JB UK Stratox Limited, The Office, Mickley, Burley Road , Langham LE15 7JB UK Stratox Limited, The Office, Mickley, Burley Road , Langham LE15 7JB UK

Tel Tel Tel Tel +44 (0) 1865 52 2341 +44 (0) 1865 52 2341 +44 (0) 1865 52 2341 +44 (0) 1865 52 2341 Email Email Email Email Info@stratox.comInfo@stratox.comInfo@stratox.comInfo@stratox.com system) Tel Tel Tel Tel +44 (0) 1865 52 2341 +44 (0) 1865 52 2341 +44 (0) 1865 52 2341 +44 (0) 1865 52 2341 Email Email Email Email Info@stratox.comInfo@stratox.comInfo@stratox.comInfo@stratox.com