Page 379 - Defrosting for Air Source Heat Pump

376 Index

Uneven defrosting (Continued) uses, 94
experimental cases, 99–100, 100t, 100f surface tension on, 136–149
experimental study, 96–98 airside surface conditions of outdoor
heat supply and energy consumption, coil, 140–141, 141–142f
108–110, 109f ASHP unit, 138
modeling study, 98–99 defrosting duration, 145–146, 146t
outdoor coil, 96, 97f energy analysis, 147–149, 147f, 148t
refrigerant distribution, 100f, 101 experimental cases, 138–139
refrigerant mass flow rate, 101–102, experimental conditions, 140t
103f, 105–106f face velocity of outdoor coil, 138, 139f
tube surface temperature, 101, 102f, fin surface temperatures, 143–145,
104–106, 107–108f 144f
five-parallel refrigerant circuit outdoor mass transfer of retained melted frost,
coil, 48, 49t,49f 139, 140f
frosting evenness coefficient, 350 tube surface temperatures, 143–145,
melted frost elimination on, 116–135 143f
airside surface conditions of outdoor three-circuit experimental study, 57–67
coil, 119, 120f, 124–126, 125f, 127f airside surface conditions, 60, 61f
ASHP unit, 118–121, 120t defrosting efficiency, 67
defrosting duration, 132–134, 133–134t downward flowing of melted frost, 60,
defrosting evenness coefficient, 132, 60t
133t experimental cases, 60
energy performance analysis, 134, 135t experimental setup, 58–59
experimental cases, 122–124 fin surface temperatures, 62, 64–65f,65
experimental conditions, 121–122, 121t, measurement/calculation errors, 59–60t
124t melted frost temperatures, 65–66, 66f
fin surface temperatures, 126, 129–130f, tailor-made three-circuit outdoor coil,
131–132 58, 59t
force analysis of retained water droplets, tube surface temperatures, 62, 62–63f
123, 123f valve location, 58f
horizontally installed three-circuit with two refrigerant circuits, 47–57
outdoor coil, 119f airside surface conditions, 50, 51f, 52,
mass transfer of retained water, 123–124, 53f
124f ASHP unit, 48–51, 48f,49t,50–51f
measurement/calculation errors, experimental cases, 51–52, 52t
121–122, 122t experimental conditions, 51, 52t
three-circuit outdoor coil, 118, 119f, 120t experimental setup, 48–51
tube surface temperatures, 126–131, fin surface temperatures, 53, 54–55f,
128–129f 55–56
vertically installed outdoor coil, 117f melted frost temperature, 53, 56, 56f
performance of, 344 RCD energy sources, 57
semiempirical mathematical models, vs. three-circuit outdoor coil, 67, 68t
73–85 tube surface temperature, 53–55,
assumptions, 75–76 54–55f
calculation conditions, 75–76
experimental validation, 86–90
limitations, 94 V
model development, 76–85, 352–367 Valve adjustment, 200–201
model extrapolation, 90–91 Vapor-injection technique, 19–22