High pressure hydrogen applications.
VPE THERMAL LLC, the subsidiary company of VPE, applies the same technology used to fabricate its diffusion bonded microchannel heat exchangers (MCHEs) on these hydrogen pre-cooling heat exchangers (H2PC®). As a result, these heat exchangers are ideally suited for high-pressure hydrogen applications.
Inside a Diffusion Bonded Microchannel Heat Exchanger
A general overview of fabricating a diffusion bonded microchannel heat exchanger, also known as a printed circuit heat exchanger:
- The VPE THERMAL® engineering team calculates the design needed to meet the requirements of the heat exchanger.
- An outside manufacturer etches plates or shims with the flow design.
- Technicians assemble the shims in a counter-flow configuration.
- The stacked plates are diffusion bonded to create a solid heat exchanger core without gaskets. Perfected since 1976, VPE’s proven diffusion bonding process ensures parent material strength throughout the core of the heat exchanger.
- The diffusion bonded core is machined to size at VPE’s machine shop.
- The welding team joins the required manifolds, flanges, and components to the core of the heat exchanger.
- A Technician carefully cleans and tests the heat exchanger to verify it is leak-proof.
- VPE THERMAL® diffusion bonded microchannel heat exchangers are “U” or “UM” stamped and meet the requirements of the ASME Boiler and Pressure Vessel Code.
Advantages of Hydrogen Pre-Cooling Heat Exchangers
There are many advantages of hydrogen pre-cooling heat exchangers (H2PC®) e.g.:
- The heat exchanger core is diffusion bonded to create a solid core without gaskets, interlayers, or brazing.
- The counter-flow configuration of the microchannels causes close-approach temperatures.
- The core design handles the maximum design pressures of the two streams at the highest temperature, which enhances safety.
- H2PC® are incredibly resistant to vibrations and catastrophic failure modes.
- Highly compact construction (high heat transfer area/volume ratio) for the productive use of small spaces relative to other configurations.
- Significant savings with low weight and fluid inventory. As a result, the H2PC® has a small footprint and can fit inside a dispenser cabinet.
- Small cooling energy overhead (small thermal mass).
- B2B fill capability is virtually infinite.
- The purchase cost meets the DOE budget, and the shipping and installation cost is low.
Hydrogen Pre-Cooling Heat Exchangers Continue to Surpass Rigorous Testing
VPE THERMAL® manufactures hydrogen pre-cooling heat exchangers (H2PC®) for high pressures and high temperatures. Additionally, we design H2PC® up to 1275 barg pressure capability. As a result, H2PC® withstand high pressures in hydrogen pre-cooling applications.
At the present time, Sandia National Laboratories studies the H2PC® which continues to easily surpass the rigorous standards.
- Sandia National Laboratories is performing the testing.
- H2PC® are surpassing the continuous and rigorous 70,000 hydrogen gas pressure cycles.
- The testing continues 24/7.
- There have been exceptional test criteria showing hermeticity to He (<10^-09 ml/sec) after cycling.
- The test pressure cycle is 0 barg to 900 barg with a ramp-up rate of 240 barg/min and with less than a second pressure ramp-down rate.
Above is a picture of a cutout of the inner core of a diffusion bonded microchannel heat exchanger (MCHE). This picture shows the layers of plates with flow channels. During diffusion bonding, the atoms diffuse together and the core becomes one solid piece at parent material strength.
For Use in Hydrogen Fueling Stations
VPE THERMAL® offers various sizes of hydrogen pre-cooling heat exchangers (H2PC®) and hydrogen recuperators for use in hydrogen fueling stations.
- There are various sizes of H2PC® for different hydrogen fill rates.
- H2PC® can handle pressures at 1000+ barg
- Hydrogen fueling stations use H2PC®.
- The hydrogen pre-cooling heat exchangers address the operational and cost targets established by the department of energy (DOE).
- H2PC® meet the SAE J2601 specifications.
Design and Operating Features for H2PC® Models
|Hydrogen fill rates in kg/min|
(SAE J2601 and beyond)
Covering forklift, light duty vehicles, heavy duty trucks, buses, trains, etc.)
|< 1||~ 2||~ 4||~ 8||~ 10||~ 12|
|Number of hydrogen side dispenser line options. |
Various nozzle orientation - easily configurable
|Single||Single and dual||Multiple|
|Typical operating inlet temperature range||20°C to 65°C|
|Operating exit temperature range|
(depending on customer application)
|0°C to -40°C
(Hydrogen recuperators use cold side hydrogen inlet at -196°C)
|Heat exchanger design temperature (Max / Min)||100°C / -196°C|
|Operating pressure range||350 barg to 950 barg|
|Heat Exchanger design pressure in barg||500 (for 350 operating); 1000 - 1275 (for > 700 operating)|
|Typical coolant types used||Syltherm XLT, R744 (CO2), Freezium-60, d-limonene, dynalene HC, Temper 60, Therminol D12, glycol-water mix, liquid nitrogen and other refrigerants|
|Typical hydrogen side connection types||Medium pressure cone and threaded fittings; Pipe butt welded nozzle option is also available|
|Typical coolant side connection type||Swagelok (straight and elbows), ANSI Flanges (CI 150 RF, CI 300 RF)|
|Typical MTTFd and design life||- MTTFd > 50 years, based on 24 hrs operation for 365 days in a 3 minute cycle operation.
- Can handle very high-pressure cycle fatigue
|Typical material of construction||SS 316L (UNS 31603)|
|Certifications||- ASME U & UM Stamps
- PED Compliant with CE marking
H2PC® Models Compared to Alternative Heat Exchangers
|PHYSICAL SIZE||Large mass and volume||Small mass and volume (high heat transfer area / volume ratio)|
|COOLING ENERGY OVERHEAD||Large cooling overhead (large thermal mass)||Small cooling overhead (small thermal mass)|
|B2B FILL CAPABILITY||HX size increases with number of B2B fills||Virtually infinite|
|PACKAGING / FOOTPRINT||Large footprint||Small foot print - Sizes range from hand-held size for mobile fueling to those that fit stationary fueling cabinets.|
|COST||Purchase cost low, shipping and installation cost high||Capital cost well below alternative. Low shipping and installation cost provide additional savings.|
Equipment & Facilities for Heat Exchangers
VPE, the parent company of VPE THERMAL®, owns over 150,000 square feet of design, lab, production, and quality assurance space. Hydrogen pre-cooling heat exchangers use the equipment and facilities below.
- Diffusion bonding furnaces
- The world’s largest vacuum hot press
- Machine shop
- Quality assurance facility
- Welding cells
- Cleaning lines
- Assembly lines
Advantages of Working With VPE
VPE, the parent company of VPE THERMAL®, provides the metallurgical services, engineering, and contract manufacturing expertise our customers require to meet their demanding performance, cost, and lead-time goals. Additionally, we work closely with OEMs, suppliers, and technology integrators to create the most efficient and effective diffusion bonded microchannel heat exchangers.
- Over 45 years of diffusion bonding experience.
- Design and manufacturing with engineering assistance.
- Tested and proven manufacturing processes.
- Redundant and burst capacity facility for fast turn and reliable sourcing.
- State-of-the-art technical facilities.
- Large-assembly diffusion bonding experience and facility.
- Developed supply chain.