def __init__(self, default_temp_shift=None):
self._default_temp_shift = default_temp_shift
self._streams = []
self._pinch_temps = []
self._cold_utility_target = 0
self._hot_utility_target = 0
self._cold_cascade = HeatCascade()
self._hot_cascade = HeatCascade()
self._shifted_cold_cascade = HeatCascade()
self._shifted_hot_cascade = HeatCascade()
self._grand_cascade = HeatCascade()
def test_hot_sensible_segment(self):
hot_segment = make_segment(180, 150, 50)
cascade = HeatCascade()
cascade.add_segments(hot_segment)
self.assertEqual(cascade.intervals, [make_segment(180, 50, 150)])
self.assertEqual(cascade.net_heat_flow(), 180)
self.assertEqual(cascade.cumulative_heat_flow(), ([0, 180], [50, 150]))
self.assertEqual(cascade.net_heat_flow(), 180)
self.assertEqual(cascade.cumulative_heat_flow(-180),
([-180, 0], [50, 150]))
def test_neutral_latent_segment(self):
neutral_segment = make_segment(0, 80, 80)
cascade = HeatCascade()
cascade.add_segments(neutral_segment)
self.assertEqual(cascade.intervals, [])
self.assertEqual(cascade.net_heat_flow(), 0)
self.assertEqual(cascade.cumulative_heat_flow(), ([], []))
self.assertEqual(cascade.cumulative_heat_flow(-100), ([], []))
def test_cold_sensible_segment(self):
cold_segment = make_segment(-180, 20, 200)
cascade = HeatCascade()
cascade.add_segments(cold_segment)
self.assertEqual(cascade.intervals, [cold_segment])
self.assertEqual(cascade.net_heat_flow(), -180)
self.assertEqual(cascade.cumulative_heat_flow(),
([0, -180], [20, 200]))
self.assertEqual(cascade.cumulative_heat_flow(50),
([50, -130], [20, 200]))
def test_cold_latent_segment(self):
cold_segment = make_segment(-200, 100, 100)
cascade = HeatCascade()
cascade.add_segments(cold_segment)
self.assertEqual(cascade.intervals, [cold_segment])
self.assertEqual(cascade.net_heat_flow(), -200)
self.assertEqual(cascade.cumulative_heat_flow(),
([0, -200], [100, 100]))
self.assertEqual(cascade.cumulative_heat_flow(-50),
([-50, -250], [100, 100]))
def test_hot_latent_segment(self):
hot_segment = make_segment(300, 150, 150)
cascade = HeatCascade()
cascade.add_segments(hot_segment)
self.assertEqual(cascade.intervals, [hot_segment])
self.assertEqual(cascade.net_heat_flow(), 300)
self.assertEqual(cascade.cumulative_heat_flow(),
([0, 300], [150, 150]))
self.assertEqual(cascade.cumulative_heat_flow(100),
([100, 400], [150, 150]))
def test_link_hot_sensible_segments(self):
hot_segments = [make_segment(80, 120, 80), make_segment(120, 80, 20)]
cascade = HeatCascade()
cascade.add_segments(*hot_segments)
self.assertEqual(cascade.intervals, [make_segment(200, 20, 120)])
self.assertEqual(cascade.net_heat_flow(), 200)
self.assertEqual(cascade.cumulative_heat_flow(), ([0, 200], [20, 120]))
def test_neutralized_heat_flow(self):
neutralizing_segments = [
make_segment(-60, 60, 120),
make_segment(60, 120, 60)
]
cascade = HeatCascade()
cascade.add_segments(*neutralizing_segments)
self.assertEqual(cascade.intervals, [])
self.assertEqual(cascade.net_heat_flow(), 0)
self.assertEqual(cascade.cumulative_heat_flow(), ([], []))
def test_detached_segments(self):
detached_segments = [
make_segment(-30, 20, 50),
make_segment(-80, 80, 120)
]
cascade = HeatCascade()
cascade.add_segments(*detached_segments)
self.assertEqual(cascade.intervals, detached_segments)
self.assertEqual(cascade.net_heat_flow(), -110)
self.assertEqual(cascade.cumulative_heat_flow(),
([0, -30, -30, -110], [20, 50, 80, 120]))
def test_overlapping_hot_segments(self):
hot_segments = [make_segment(60, 120, 60), make_segment(130, 85, 20)]
expected_intervals = [
make_segment(80, 20, 60),
make_segment(75, 60, 85),
make_segment(35, 85, 120),
]
cascade = HeatCascade()
cascade.add_segments(*hot_segments)
self.assertEqual(cascade.intervals, expected_intervals)
self.assertEqual(cascade.net_heat_flow(), 190)
self.assertEqual(cascade.cumulative_heat_flow(),
([0, 80, 155, 190], [20, 60, 85, 120]))
def test_link_latent_segments(self):
latent_segments = [
make_segment(-200, 100, 100),
make_segment(-150, 100, 100),
make_segment(250, 100, 100),
]
expected_intervals = [make_segment(-100, 100, 100)]
cascade = HeatCascade()
cascade.add_segments(*latent_segments)
self.assertEqual(cascade.intervals, expected_intervals)
self.assertEqual(cascade.net_heat_flow(), -100)
self.assertEqual(cascade.cumulative_heat_flow(),
([0, -100], [100, 100]))
def test_detached_latent_segments(self):
latent_segments = [
make_segment(-200, 100, 100),
make_segment(-150, 200, 200)
]
cascade = HeatCascade()
cascade.add_segments(*latent_segments)
self.assertEqual(cascade.intervals, latent_segments)
self.assertEqual(cascade.net_heat_flow(), -350)
self.assertEqual(
cascade.cumulative_heat_flow(),
([0, -200, -200, -350], [100, 100, 200, 200]),
)
def test_add_latent_then_sensible_segment(self):
latent_then_sensible = HeatCascade()
latent_then_sensible.add_segments(make_segment(-200, 100, 100),
make_segment(-80, 80, 120))
expected_intervals = [
make_segment(-40, 80, 100),
make_segment(-200, 100, 100),
make_segment(-40, 100, 120),
]
self.assertEqual(latent_then_sensible.intervals, expected_intervals)
self.assertEqual(latent_then_sensible.net_heat_flow(), -280)
self.assertEqual(
latent_then_sensible.cumulative_heat_flow(),
([0, -40, -240, -280], [80, 100, 100, 120]),
)
def test_overlapping_cold_segments(self):
cold_segments = [
make_segment(-65, 20, 85),
make_segment(-120, 60, 120)
]
expected_intervals = [
make_segment(-40, 20, 60),
make_segment(-75, 60, 85),
make_segment(-70, 85, 120),
]
cascade = HeatCascade()
cascade.add_segments(*cold_segments)
self.assertEqual(cascade.intervals, expected_intervals)
self.assertEqual(cascade.net_heat_flow(), -185)
self.assertEqual(cascade.cumulative_heat_flow(),
([0, -40, -115, -185], [20, 60, 85, 120]))
def test_mixed_sensible_segments(self):
mixed_segments = [
make_segment(-60, 60, 120),
make_segment(-10, 60, 70),
make_segment(130, 85, 20),
]
expected_intervals = [
make_segment(80, 20, 60),
make_segment(15, 70, 85),
make_segment(-35, 85, 120),
]
cascade = HeatCascade()
cascade.add_segments(*mixed_segments)
self.assertEqual(cascade.intervals, expected_intervals)
self.assertEqual(cascade.net_heat_flow(), 60)
self.assertEqual(cascade.cumulative_heat_flow(),
([0, 80, 80, 95, 60], [20, 60, 70, 85, 120]))
def test_add_cascades(self):
cold_cascade = HeatCascade()
cold_cascade.add_segments(make_segment(-230, 25, 140))
cold_cascade.add_segments(make_segment(-240, 85, 145))
hot_cascade = HeatCascade()
hot_cascade.add_segments(make_segment(330, 165, 55))
hot_cascade.add_segments(make_segment(180, 145, 25))
mixed_cascade = HeatCascade()
mixed_cascade.add_segments(*cold_cascade.intervals)
mixed_cascade.add_segments(*hot_cascade.intervals)
self.assertEqual(
mixed_cascade.intervals,
[
make_segment(-15, 25, 55),
make_segment(75, 55, 85),
make_segment(-82.5, 85, 140),
make_segment(2.5, 140, 145),
make_segment(60, 145, 165),
],
)
self.assertEqual(mixed_cascade.net_heat_flow(), 40)
self.assertEqual(
mixed_cascade.cumulative_heat_flow(),
([0, -15, 60, -22.5, -20, 40], [25, 55, 85, 140, 145, 165]),
)
self.assertEqual(
mixed_cascade.cumulative_heat_flow(22.5),
([22.5, 7.5, 82.5, 0, 2.5, 62.5], [25, 55, 85, 140, 145, 165]),
)
class PinchAnalyzer:
"""
This class performs pinch analysis calculations on a list of streams:
heating and cooling requirements, heat cascades and the pinch
temperature(s).
"""
def __init__(self, default_temp_shift=None):
self._default_temp_shift = default_temp_shift
self._streams = []
self._pinch_temps = []
self._cold_utility_target = 0
self._hot_utility_target = 0
self._cold_cascade = HeatCascade()
self._hot_cascade = HeatCascade()
self._shifted_cold_cascade = HeatCascade()
self._shifted_hot_cascade = HeatCascade()
self._grand_cascade = HeatCascade()
@property
def cooling_demand(self):
return self._hot_cascade.net_heat_flow()
@property
def heating_demand(self):
return self._cold_cascade.net_heat_flow()
@property
def cold_utility_target(self):
return self._cold_utility_target
@property
def hot_utility_target(self):
return self._hot_utility_target
@property
def heat_recovery_target(self):
return self.heating_demand - self.hot_utility_target
@property
def pinch_temps(self):
return self._pinch_temps
@property
def default_temp_shift(self):
return self._default_temp_shift
@property
def streams(self):
return self._streams
@property
def cold_composite_curve(self):
return self._cold_cascade.cumulative_heat_flow(
self.cold_utility_target)
@property
def hot_composite_curve(self):
return self._hot_cascade.cumulative_heat_flow()
@property
def shifted_cold_composite_curve(self):
return self._shifted_cold_cascade.cumulative_heat_flow(
self.cold_utility_target)
@property
def shifted_hot_composite_curve(self):
return self._shifted_hot_cascade.cumulative_heat_flow()
@property
def grand_composite_curve(self):
return self._grand_cascade.cumulative_heat_flow(
self.cold_utility_target)
def add_streams(self, *streams):
"""
Adds the given streams to the stream group.
"""
for s in streams:
self._add_one(s)
self._compute_targets()
def _add_one(self, stream):
self._streams.append(stream)
for s in stream.cold_segments:
self._cold_cascade.add_segments(s.with_absolute_heat_flow())
shifted = s.shift(self.default_temp_shift)
self._shifted_cold_cascade.add_segments(
shifted.with_absolute_heat_flow())
self._grand_cascade.add_segments(shifted.with_inverted_heat_flow())
for s in stream.hot_segments:
self._hot_cascade.add_segments(s.with_absolute_heat_flow())
shifted = s.shift(self.default_temp_shift)
self._shifted_hot_cascade.add_segments(
shifted.with_absolute_heat_flow())
self._grand_cascade.add_segments(shifted.with_inverted_heat_flow())
def _compute_targets(self):
heat_flows, temps = self._grand_cascade.cumulative_heat_flow()
if heat_flows:
min_heat_flow = min(heat_flows)
self._pinch_temps = [
t for t, h in zip(temps, heat_flows) if h == min_heat_flow
]
self._cold_utility_target = heat_flows[0] - min_heat_flow
self._hot_utility_target = heat_flows[-1] - min_heat_flow
else:
self._pinch_temps = []
self._cold_utility_target = 0
self._hot_utility_target = 0
def test_touching_segments(self):
cold_segments = [make_segment(-60, 20, 80), make_segment(-80, 80, 120)]
cold_cascade = HeatCascade()
cold_cascade.add_segments(*cold_segments)
self.assertEqual(cold_cascade.intervals, cold_segments)
self.assertEqual(cold_cascade.net_heat_flow(), -140)
self.assertEqual(cold_cascade.cumulative_heat_flow(),
([0, -60, -140], [20, 80, 120]))
hot_segments = [make_segment(80, 120, 80), make_segment(60, 80, 20)]
hot_cascade = HeatCascade()
hot_cascade.add_segments(*hot_segments)
self.assertEqual(hot_cascade.intervals,
[make_segment(60, 20, 80),
make_segment(80, 80, 120)])
self.assertEqual(hot_cascade.net_heat_flow(), 140)
self.assertEqual(hot_cascade.cumulative_heat_flow(),
([0, 60, 140], [20, 80, 120]))
def test_empty(self):
cascade = HeatCascade()
self.assertEqual(cascade.intervals, [])
self.assertEqual(cascade.net_heat_flow(), 0)
self.assertEqual(cascade.cumulative_heat_flow(), ([], []))
self.assertEqual(cascade.cumulative_heat_flow(-100), ([], []))
def test_equality_comparison(self):
cascade = HeatCascade()
self.assertEqual(cascade, HeatCascade())
compare_to = HeatCascade()
compare_to.add_segments(make_segment(-230, 25, 140),
make_segment(-240, 85, 145))
self.assertNotEqual(cascade, compare_to)
cascade.add_segments(make_segment(-230, 25, 140))
self.assertNotEqual(cascade, compare_to)
cascade.add_segments(make_segment(-240, 85, 145))
self.assertEqual(cascade, compare_to)