Propane Liquefaction with an Active Magnetic Regenerative Liquefier
Magnetic refrigeration is a cooling technique that uses the magnetocaloric e?ect (MCE). The active magnetic regenerator (AMR) cycle is a regenerative cycle that employs the MCE and consists of four steps: adiabatic magnetization with no heat transfer gas flow; heat transfer gas flow at constant high field; demagnetization with no heat transfer gas flow; and heat transfer gas flow at constant low field. The first heat transfer gas cold-to-hot flow step rejects heat from the magnetized regenerator to a hot sink and the second reverse heat transfer gas hot-to-cold flow step add heat from a cold source into the demagnetized regenerator. Our primary research and development objective is to use the MCE for more efficient liquefaction of much colder cryogens, to help identify problems of effective coupling of cold heat transfer gas of a single-stage reciprocating magnetic refrigerator to a process gas, we have used a single-stage active magnetic regenerative refrigerator (AMRR) with Gd refrigerant to liquefy pure propane gas at two different supply pressures. The high-purity propane was supplied from a small regulated lecture bottle at 295 K via a 1.6 mm o.d. stainless-steel tube into the helium-cooled coiled-fin tube heat exchanger at 49 psia or 27 psia, to liquefy propane at 262 K or 246 K, respectively. Propane liquefied until the small collection vessel and the coiled fin tube heat exchanger were filled at which the flow from the open lecture bottle stopped. The measured rate of liquefaction and the elapsed time for each case were measured and used to determine the volume of propane collected and the cooling power of the AMRR at the liquefaction temperatures. These cooling power results were compared to the cooling power results obtained from the curve of cool-down temperature vs. time data and agreement was excellent after the duty cycle of each cooling process was properly treated.