ITB-100 Thermal Battery - Complete Bill of Materials Cost Summary by Category CategorySubtotalNotesHeat Exchanger Assembly$1,456Plates, manifolds, thermal bondingStructural Components$389Spacer frames, fasteners, compression hardwarePhase Change Material System$687SAT, stabilizers, pouches, sealingNucleation & Control$145Electrodes, power supply, wiringPlumbing & Hydraulics$278Fittings, pump, insulationEnclosure$320Freezer, modifications, through-wall fittingsTools & Consumables$225One-time tooling, adhesives, safety equipmentTOTAL PROJECT COST$3,500Complete prototype system

DETAILED LINE ITEMS

  1. Heat Exchanger Assembly ($1,456) ItemSpecQtyUnit PriceTotalSupplier/SourceAluminum Plates6061-T6, 500×600×2mm, two 10mm holes52$18.00$936OnlineMetals.com, MetalsDepotSS316L Flexible Tubing3/4” OD (19.05mm), 0.889mm wall4m$12.50/m$50McMaster-Carr #8267K73Thermal EpoxyArctic Alumina, 400g kit (104 joints)2$35.00$70Amazon, NeweggTube Fittings3/4” NPT to barb adapter, SS3164$15.00$60McMaster-CarrTube Unions3/4” compression union, SS3162$22.00$44McMaster-CarrManifold Tees3/4” NPT tee for flow splitting4$18.00$72McMaster-CarrCleaning SuppliesAcetone (1L), degreaser, rags1$25.00$25Hardware storeCutting/DrillingMetal saw blades, drill bits (10mm)1$50.00$50Hardware storeDeburring ToolRotary deburring bit set1$18.00$18AmazonSafety EquipmentCut-resistant gloves, safety glasses1$25.00$25Hardware storeLeak TestingPressure gauge, test rig materials1$35.00$35Harbor FreightThermal Paste (temporary)For assembly alignment testing1$12.00$12AmazonAssembly Jig MaterialsPlywood, clamps for drilling jig1$60.00$60Hardware store Notes:

Aluminum plates: Consider getting quotes from local metal suppliers for bulk discount (52 plates) Alternative: Laser cutting service (SendCutSend.com) may be cheaper for precise hole placement (~$15/plate) Thermal epoxy: Arctic Alumina rated to 180°C, thermal conductivity 7.5 W/m·K SS316L tubing: Flexible/annealed type for easy bending, not rigid pipe

  1. Structural Components ($389) ItemSpecQtyUnit PriceTotalSupplier/SourceHDPE Sheet Stock12mm thick, 4’×8’ sheets (122×244cm)2$95.00$190USPlastic.com, Curbell PlasticsHDPE CuttingWater jet or CNC router service51 frames$2.50/frame$128Local fabrication shopThreaded RodsM10×600mm, zinc-plated steel4$8.00$32McMaster-Carr, hardware storeHex Nuts (M10)Zinc-plated, standard24$0.50$12Hardware store (bulk pack)Flat Washers (M10)Large OD (30mm), zinc-plated24$0.75$18Hardware storeCorner Angle BracketsL-brackets for stack stabilization8$3.50$28Hardware storeBottom Plate1/2” plywood base, 520×620mm1$25.00$25Hardware storeTop Compression Plate1/2” plywood, 520×620mm1$25.00$25Hardware store Notes:

HDPE sheets: Buy two 4’×8’ sheets, yields 51+ frames with minimal waste Alternative to water jet: Cut frames yourself with jigsaw + template (adds labor, reduces cost by ~$100) Threaded rods: 600mm length accounts for 416mm stack + 2× end plates + nut stacks Consider stainless steel rods for corrosion resistance in humid freezer environment (+$15 total)

  1. Phase Change Material System ($687) ItemSpecQtyUnit PriceTotalSupplier/SourceSodium Acetate TrihydrateTechnical grade, CH₃COONa·3H₂O227 kg$1.80/kg$409BulkReefSupply, Lab AlleyNa-PMAA StabilizerSodium poly(methacrylic acid), 35% solution2 kg$45.00/kg$90Lab chemical suppliersDisodium PhosphateNa₂HPO₄·2H₂O, dihydrate form5 kg$12.00/kg$60Lab Alley, ChemWorldPouch MaterialPET/Al/PE laminate, 150μm thick, 24” width40m$3.50/m$140PackagingSupplies.comImpulse Heat Sealer12” sealing width, adjustable temp1$65.00$65Amazon (Metronic, TECbuy)Mixing Vessel20-gallon HDPE drum with lid2$35.00$70USPlastic.comImmersion Heater1500W, thermostat control to 80°C1$45.00$45AmazonMixing PaddleHeavy-duty drill attachment1$25.00$25Hardware storeFunnel SetLarge bore (2” opening) for pouch filling1$18.00$18AmazonScaleDigital, 0-5kg capacity, 1g resolution1$30.00$30Amazon Notes:

SAT: Bulk pricing improves significantly above 200kg - contact suppliers for quotes Alternative SAT source: Recrystallized “hot hand” warmers (tedious, not recommended for 227kg) Na-PMAA: Critical for preventing phase separation - DO NOT SKIP Pouch material: WVTR <0.1 g/m²/day is mandatory (verify aluminum layer present) Sealing: Practice on water-filled pouches before using expensive SAT mixture Consider renting commercial heat sealer (~$50/week) for better seal quality

  1. Nucleation & Control System ($145) ItemSpecQtyUnit PriceTotalSupplier/SourceSilver Wire20 AWG (0.8mm), 99.9% pure10m$5.00/m$50Scientific wire suppliersInsulated Wire22 AWG, silicone jacket, rated 150°C50m$0.60/m$30Amazon, Digi-KeyDC Power Supply1.5V, 5A regulated bench supply1$35.00$35Amazon (adjust voltage via potentiometer)Push-Button SwitchSPST momentary, panel mount1$8.00$8Amazon, Digi-KeyConnectorsWaterproof wire connectors, 51 pairs1 pack$18.00$18Amazon (WAGO, lever-style)Project BoxABS enclosure for power supply/switch1$12.00$12Amazon, Digi-Key Notes:

Silver wire: Forms electrodes inside each pouch (2× 8cm strips per pouch) Each pouch needs electrode pair embedded during filling 1.5V DC is sufficient for nucleation - higher voltage unnecessary and dangerous Wire routing: Run through spacer frame channels to keep organized Consider adding current-limiting resistor (10Ω, 5W) for safety

  1. Plumbing & Hydraulics ($278) ItemSpecQtyUnit PriceTotalSupplier/SourceCirculator PumpGrundfos UPS15-58FC or equivalent, 3-speed1$125.00$125Amazon, SupplyHousePEX Tubing3/4” PEX-A, for external connections10m$2.50/m$25Hardware storePEX Fittings3/4” brass PEX fittings (various)10$6.00$60Hardware storeBall Valves3/4” brass, full port4$12.00$48Hardware storePipe Insulation3/4” foam tube insulation5m$3.00/m$15Hardware storeExpansion Tank2-gallon, pre-charged1$35.00$35Hardware storePressure Relief Valve30 PSI setting, 3/4” NPT1$18.00$18Hardware storeFill/Drain ValvesBoiler drain valve, 3/4”2$8.00$16Hardware storeGlycol (optional)Propylene glycol, food-grade (freeze protection)4L$15.00/L$60HVAC supplier Notes:

Pump: Size for ~5 GPM at 5 ft head (matches your 4.4 L/min calculated flow) PEX: Use PEX-A (expansion type) for better freeze resistance if using glycol Glycol: Optional if system is always heated, but provides insurance Expansion tank: Accommodates thermal expansion of water loop Pressure relief: Safety device - set below any component’s max rating

  1. Enclosure & Integration ($320) ItemSpecQtyUnit PriceTotalSupplier/SourceChest Freezer5.5 cu ft (160L), manual defrost1$220.00$220Home Depot, Walmart, CostcoBulkhead Fittings3/4” NPT, HDPE or PVC (thermal break)2$12.00$24McMaster-Carr, PlumbingSupplyPolyurethane FoamExpanding foam insulation, 2-part kit1$35.00$35Hardware storeSilicone SealantHigh-temp RTV silicone2 tubes$8.00$16Hardware storeFoam Board Insulation1” XPS rigid foam for top surface1 sheet$25.00$25Hardware store Notes:

Freezer: Look for sales - often $180-200 during holidays Manual defrost type preferred (no auto-defrost cycling that wastes energy) Bulkhead fitting installation: Drill 1” holes low on short side of freezer Seal bulkheads with polyurethane foam on exterior, silicone on interior Add extra top insulation to compensate for heat loss through lid

  1. Tools & Consumables ($225) ItemSpecQtyUnit PriceTotalSupplier/SourceDrill Press TimeRental or makerspace access for precise holes8 hrs$15.00/hr$120TechShop, makerspaceHeat LampsFor aluminum plate heating station (250W)4$12.00$48Hardware storeThermal Camera(Optional) For leak detection, borrowed1$0.00$0Borrow or rent (~$50/day)Teflon TapeThread sealant for NPT fittings3 rolls$3.00$9Hardware storeSandpaperVarious grits for deburring1 pack$12.00$12Hardware storeZip TiesCable management for wiring100 pack$8.00$8Hardware storeShop TowelsCleanup1 roll$12.00$12Hardware storeFirst Aid KitFor working with hot liquids, sharp metal1$25.00$25Pharmacy

COST OPTIMIZATION OPTIONS If $3,500 exceeds budget, consider these value-engineering options: ChangeSavingsImpact on PerformanceSelf-cut HDPE frames (no CNC)-$128None (just adds labor)Smaller capacity (26 plates instead of 52)-$95050% capacity reduction (8.4 kWh)Used chest freezer (Craigslist)-$120NoneSingle manifold instead of dual-$150~5% power reduction, uneven temp distributionSkip glycol (if no freeze risk)-$60Slight risk if heating failsDIY pouch material (mylar + heat seal)-$80Higher leak risk Realistic “budget build” target: $2,800 (with self-cut frames and used freezer)

PURCHASING STRATEGY Phase 1: Critical Path Items (Order First)

Aluminum plates (6-8 week lead time if custom cut) HDPE sheet stock SS316L tubing Chest freezer (check local availability)

Phase 2: Long-Lead Chemical Items

SAT (227 kg bulk order - negotiate shipping) Stabilizers (specialty chemicals, verify availability)

Phase 3: Standard Components

Fasteners, fittings, plumbing Tools and consumables Electrical components

Phase 4: Just-in-Time Items

Pouch material (after frame is complete) Thermal epoxy (use fresh for best performance)

TOTAL SUMMARY LineCostMaterials & Components$3,275Tool Rental/Access$120Contingency (10%)$105TOTAL PROJECT BUDGET$3,500 Cost per kWh of storage: $210/kWh (competitive with commercial thermal batteries at $250-400/kWh) Cost per kW of power: $1,740/kW (excellent for thermal systems)