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Infinity Turbine CO2 Turbine Development and Testing Cart Supercritical CO2 Turbine Development Cart using high pressure filter canisters for rapid prototyping and commercialization for 1-25 kWh Power Generation... More Info
ORC and sCO2 Performance Charts: R134a, R245fa, CO2 – 2026 Edition Updated 2026 edition of Infinity Turbine’s ORC and supercritical CO2 performance curves: R134a, R245fa and CO2 charts, CO2 heat-rate tables from 100 to 700 °C, sCO2 turbine types, and data-center applications. 62-page PDF... More Info
Supercritical CO2 Turbine Generator Plans (Transcritical) Rankine Cycle Lab format for development ... More Info
Matra Concentrated Solar Project Using Infinity Turbine Generator for Power Production Solar thermal power production using a reflective dish concentrator... More Info
Cluster Mesh Supercritical CO2 Power System for Data Centers and AI Pairing Cluster Mesh Supercritical CO2 Power System with Small Modular Reactors enables hyperscalers to convert high-grade nuclear heat into ultra-efficient, dispatchable power with a compact, modular footprint tailored for AI-scale demand. More Info
ORC and Products Index Infinity Turbine ORC Index... More Info
A Generator Without Magnets Switched Reluctance is the simplest rotating electrical machine there is: a rotor of stacked steel laminations with salient teeth, and a stator carrying concentrated coils. The rotor has no magnets, no windings, no bars and no slip rings... More Info
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Technical Assessment Technical AssessmentConcept recap:A closed‑loop CO₂ circuit is heated and pressurized, then expanded to a lower pressure to create a cold stream. Liquid water is exposed to this cold stream to form ice. The CO₂ is then cooled and condensed to liquid, pumped back up in pressure, passed through a heat exchanger, and the cycle repeats. Ice is harvested for use.1) Thermodynamic feasibility Working fluid: CO₂ (R‑744) is a proven refrigerant. Its critical point is 31.1 °C and 73.8 bar. Below the critical temperature (e.g., with a cool heat sink), the cycle can condense to liquid and use a liquid pump for pressurization. Above it, the system operates transcritically and needs a compressor instead of a pump. Cold production: Cooling is produced during expansion (throttling/Joule–Thomson or via an expander) followed by evaporation at low pressure. This can readily reach the temperature margin to freeze water, provided the evaporator is at or below \~−5 to −15 °C. Avoiding dry ice: CO₂’s triple point is −56.6 °C at \~5.2 bar. The design must keep the low side above the triple‑point pressure to avoid dry‑ice formation and blockage.2) Cycle architecture options Subcritical, pump‑driven (your description): If the heat sink (ambient, groundwater, or cooling tower) can cool the high side below 31 °C, CO₂ can be fully condensed. Then a liquid pump raises pressure efficiently. Important: add heat after pressurization mainly to reject it again at the condenser/gas cooler; you do not want to intentionally heat before expansion, since that reduces net refrigeration. The liquid should be cooled as much as possible before expansion to maximize the refrigeration effect. Transcritical, compressor‑driven: If ambient is warm (common), the system runs transcritical with a gas cooler (not a condenser) and a compressor. This is common in CO₂ refrigeration, and ice making is practical, but you lose the “liquid pump” efficiency benefit.3) Ice formation method Indirect freezing (recommended): Use a scraped‑surface or plate evaporator. Water flows on one side; CO₂ evaporates on the other. Ice forms on metal surfaces and is harvested (flaked or released). This avoids CO₂–water contact, contamination, and blockage risk. Direct‑contact spray into cold CO₂ (not recommended): Spraying water directly into the low‑pressure CO₂ stream risks entraining moisture, forming slush/ice inside the CO₂ side, fouling valves, and complicating oil management. It also complicates dehydration of the refrigerant loop.4) Efficiency (COP) considerations Liquid pump advantage: When subcritical, using a pump instead of a compressor to raise pressure can improve COP because pumping a liquid requires far less work than compressing a gas. Expected COP: For ice‑making temperatures, a practical CO₂ system may achieve COP ≈ 1.5–3.0, depending on ambient temperature, heat exchanger approach, and whether you recover expansion work (expander/ejector). Ballpark energy: Freezing 1 kg of 25 °C water requires ~~418 kJ of cooling (to chill to 0 °C and freeze). With COP = 2.5, input energy ≈ 0.046 kWh/kg (~~42 kWh per metric ton of ice), excluding auxiliaries. Upgrades: Expander (instead of a throttling valve) to recover work and boost COP. Ejector to lift suction pressure and reduce throttling losses. Parallel compression and flash gas management to optimize transcritical performance.5) Equipment & control Key components: condenser/gas cooler, liquid receiver, liquid pump (subcritical mode), expansion valve or turbine expander, low‑temperature evaporator designed for ice duty, oil management, drier, and precise pressure controls to keep P\_low > 5.2 bar. Water side: consider scraped‑surface evaporators (flake ice), falling‑film plates, or ice‑slurry generators. Include water treatment to minimize scaling and defrost/harvest strategy. Safety: CO₂ operates at high pressures; design for >120 bar on the high side with certified vessels, PRVs, and gas detection.6) Risks & mitigations Dry ice risk: Maintain adequate low‑side pressure; use robust control logic. Frosting/blocking: Prefer indirect heat exchange; use scraped surfaces. Warm climates: If you cannot condense (T\_ambient > 31 °C), expect transcritical operation and size the gas cooler and controls accordingly. Water quality: Scale and biofouling reduce capacity; treat or filter feedwater.Bottom line: The concept is feasible and well‑aligned with established CO₂ refrigeration practice if you (a) avoid direct water injection into the CO₂ stream, (b) keep the evaporator above the triple‑point boundary, and (c) select subcritical or transcritical architecture based on your heat sink. A subcritical, liquid‑pump cycle can be very efficient where you can reliably condense below 31 °C. |
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Can carbon dioxide be the heart of an efficient ice‑making system? Yes—if you manage pressures, temperatures, and ice formation wisely. Here’s how. IntroductionAs demand for efficient, climate‑friendly refrigeration grows, carbon dioxide (CO₂, R‑744) has reemerged as a compelling working fluid. Its favorable thermophysical properties, non‑flammability, and negligible GWP compared with legacy refrigerants make it attractive for ice production—provided the cycle is engineered correctly.How the CO₂ Ice Cycle WorksA CO₂ ice system circulates the refrigerant in a sealed loop. On the high side, heat is rejected in a condenser or gas cooler. If the heat sink is cool enough to condense below the 31.1 °C critical temperature, the refrigerant becomes a liquid. A liquid pump can then raise pressure with minimal work input. The liquid is subcooled as much as possible and expanded across a valve—or, better, an expander. The low‑pressure stream becomes cold, feeding an evaporator that freezes water into ice. The CO₂ vapor returns to the high side, and the cycle repeats.In warmer climates, the same concept runs transcritically using a compressor and a gas cooler. Control of gas cooler outlet temperature and high‑side pressure is central to performance.Making Ice Without Fouling the RefrigerantThe most reliable approach is indirect: water flows across a cold evaporator surface while CO₂ boils inside the tubes. Ice forms as flakes or releases from plates during a harvest cycle. This avoids direct contact between water and refrigerant, keeps the CO₂ loop dry, and eliminates slush blockages.Efficiency ConsiderationsWhen subcritical, pumping liquid CO₂ instead of compressing gas can significantly improve efficiency. With good heat exchanger design and smart controls, practical systems can reach COP values in the 1.5–3.0 range for ice‑making temperatures. Adding an expander or ejector reduces throttling losses and can provide a meaningful boost in capacity and COP.Design Notes and Safety Keep the suction pressure safely above the CO₂ triple point to avoid dry‑ice formation. Use vessels, piping, and valves rated for high pressures, and install pressure relief and gas detection. Treat water to limit scale on ice‑contact surfaces, and select an ice‑harvest strategy (scraped surface, plate release, or slurry) that matches your product form and capacity.When CO₂ Makes SenseCO₂ is particularly attractive where a cool heat sink is available for subcritical operation or where regulatory drivers favor natural refrigerants. For large, industrial ice production with waste‑heat recovery and careful controls, CO₂ provides a modern, sustainable alternative to legacy fluids.ConclusionA closed‑loop CO₂ cycle can produce ice efficiently and safely when engineered around its unique pressure‑temperature map. Choose the right architecture (subcritical with a pump or transcritical with a compressor), isolate the water from the refrigerant, and control the expansion process. Do that well, and CO₂ delivers clean, scalable ice production. |
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