Calculate the density of liquid ethylene at various temperatures and pressures. Includes saturation properties, compressibility, and phase behavior.
Ethylene (C₂H₄) is the world's most produced organic chemical, with annual global production exceeding 200 million tonnes. In its liquid state, ethylene is a cryogenic fluid with a boiling point of −103.7°C at atmospheric pressure and a critical temperature of 9.2°C. Accurate density data for liquid ethylene is essential for process design, storage tank sizing, pipeline engineering, and metering in the petrochemical industry.
Liquid ethylene density varies significantly with temperature and pressure. At its normal boiling point (−103.7°C, 1 atm), liquid ethylene has a density of approximately 567 kg/m³. As temperature increases toward the critical point (9.2°C, 50.4 bar), density decreases substantially, approaching the critical density of 214 kg/m³. Above the critical temperature, ethylene exists as a supercritical fluid where liquid and gas phases are indistinguishable.
This calculator uses established correlations to estimate liquid ethylene density across a wide range of conditions encountered in industrial practice. From cryogenic storage at atmospheric pressure to high-pressure pipeline transport, the density values help engineers calculate mass flow rates, determine vessel sizing, and ensure safe material handling. Understanding ethylene's thermophysical properties is fundamental to the design and operation of ethylene crackers, polyethylene reactors, and refrigeration systems.
Essential for petrochemical engineers designing ethylene storage, transport, and processing systems. Calculate density for tank gauging, pipeline sizing, and heat exchanger design. Also useful for cryogenic engineering and refrigeration system design. This liquid ethylene density calculator helps you compare outcomes quickly and reduce avoidable mistakes when making day-to-day care decisions. Use the estimate as a planning baseline and confirm final decisions with a qualified professional when risk is high.
Rackett Equation (modified): ρ = (Pc/(R×Tc)) × Zc^(1+(1−Tr)^(2/7)), where Tr = T/Tc is reduced temperature, Tc = 282.34 K, Pc = 50.42 bar, Zc = 0.281. For ethylene: MW = 28.054 g/mol, Tb = 169.42 K (−103.73°C), critical density ρc = 214.2 kg/m³.
Result: Liquid density ≈ 567 kg/m³
At the normal boiling point (−103.7°C, 1 atm), liquid ethylene has a density of approximately 567 kg/m³. This is about 56.7% the density of water and nearly 500× the density of ethylene gas at STP.
Ethylene is the primary feedstock for polyethylene (HDPE, LDPE, LLDPE), ethylene oxide, ethylene dichloride, and styrene — products that form the backbone of the plastics and chemicals industry. Steam crackers produce ethylene by thermal decomposition of hydrocarbons (ethane, naphtha, gas oil) at 800-900°C. The product ethylene is then purified by cryogenic distillation at temperatures down to −160°C, where accurate thermophysical property data is critical for column design and operation.
Large-scale ethylene storage uses fully refrigerated tanks operating near atmospheric pressure at −104°C. These double-wall, insulated tanks can hold up to 60,000 m³ of liquid ethylene. Ethylene is also transported by pipeline (over 30,000 km of ethylene pipelines exist globally), typically as a dense-phase or supercritical fluid. Pipeline design requires accurate density and viscosity data across the operating temperature and pressure range. For marine transport, semi-pressurized or fully-refrigerated ethylene carriers transport up to 12,000 m³ per voyage.
Ethylene is lighter than propylene (liquid density ~610 kg/m³ at NBP) and butane (~584 kg/m³). Its critical temperature (9.2°C) is much lower than propane (96.7°C) or butane (152°C), meaning it requires cryogenic conditions for liquefaction at moderate pressures. Methane, the lightest hydrocarbon, has even lower critical temperature (−82.6°C). This progression explains why natural gas (mostly methane) requires LNG technology at −162°C, while LPG (propane/butane) can be stored as liquid at ambient temperature under modest pressure.
Ethylene is transported and stored as a cryogenic liquid. Accurate density is needed for tank level gauging, custody transfer metering, pipeline hydraulics, and process design calculations. A 1% density error in a large storage tank translates to tonnes of inventory error.
Ethylene's critical point is Tc = 9.2°C (282.34 K), Pc = 50.42 bar (731 psi), ρc = 214.2 kg/m³. Above these conditions, ethylene is supercritical and distinct liquid/gas phases don't exist.
Liquid ethylene is stored at atmospheric pressure in cryogenic tanks at −104°C, or at ambient temperature under pressure (~40-70 bar depending on temperature). Refrigerated storage is more common for large quantities due to lower pressure vessel costs.
At STP, ethylene gas has density ~1.18 kg/m³. Liquid ethylene at its boiling point is ~567 kg/m³ — about 480 times denser. This massive density difference is why liquefaction is preferred for transport and storage.
Liquids are relatively incompressible. Increasing pressure from 1 to 50 bar increases density by only 1-3% for subcooled liquid ethylene. Near the critical point, however, compressibility increases dramatically.
Yes, ethylene (R-1150) is used in cascade refrigeration systems for achieving very low temperatures (down to −100°C). It's common in LNG plants and ethylene plants themselves. Its favorable thermodynamic properties make it efficient for cryogenic service.