A theoretical study on the performance of a scroll expander in an organic Rankine cycle with hydrofluoroolefins (HFOs) in place of R245fa

Design and performance of a miniature free piston expander

“…To generate a pressure-volume diagram, the model Eqs. [7][8][9][10] is numerically integrated in the order 1→2→3→4→5→1 ( Fig. 1) starting with state 1: ∆V 1 , ∆P 1 , ∆T 1 , ∆V 1 = 0.…”

“…The resulting volume ∆V 2 , pressure ∆P 2 , and temperature ∆T 2 from the first phase of the injection process, 1→2 is computed by numerically integrating Eqs. [7][8][9][10] from the initial condition ∆V 1 , ∆P 1 , ∆T 1 , ∆V 1 = 0 for a timet 12 such that the CV pressure P 2 equals injection pressure P 2 = P i . The resulting volume ∆V 3 , pressure ∆P 3 , and temperature ∆T 3 during the second phase (timed injection) of the injection process, 2→3 is computed by numerically integrating Eqs.…”

“…The resulting volume ∆V 3 , pressure ∆P 3 , and temperature ∆T 3 during the second phase (timed injection) of the injection process, 2→3 is computed by numerically integrating Eqs. [7][8][9][10] from the initial condition ∆V 2 , ∆P 2 , ∆T 2 , ∆V 2 for a predetermined time durationt 23 . The volumes, pressures, and temperatures ∆V 4 , ∆P 4 , ∆T 4 and ∆V 1 , ∆P 1 , ∆T 1 from the expansion and exhaust (displacement phase) processes 3→4 and 5→1 are computed by numerically integrating Eqs.…”

“…The volumes, pressures, and temperatures ∆V 4 , ∆P 4 , ∆T 4 and ∆V 1 , ∆P 1 , ∆T 1 from the expansion and exhaust (displacement phase) processes 3→4 and 5→1 are computed by numerically integrating Eqs. [7][8][9][10] from the initial conditions ∆V 3 , ∆P 3 , ∆T 3 , ∆V 3 and ∆V 5 , ∆P 5 , ∆T 5 , ∆V 5 = 0 for timest 34 andt 51 , respectively such that the piston velocity ∆V 4 = ∆V 1 = 0. It is worth nothing that the timest 12 ,t 34 ,t 51 are 'a priori ' and is determined during the integration.…”

“…Typically, low temperature harvesters are based on an Organic Rankine Cycle (ORC) [2,3,4,5] which employs refrigerant (e.g. HCFC-123) as a working fluid [6,7,8] in traditional high-speed turbines [9] and crankshaft-based piston expanders [10], and less popular screw [11] and scroll expanders [12]. Most ORC-based harvesters are macroscale systems which benefit from scaling laws that offer high manufacturing tolerances, less heat loss, and less pumping work.…”