Page 377 - Defrosting for Air Source Heat Pump

374 Index

Refrigerant distribution (Continued) refrigeration adjustment valve, influence of
melted frost flowing cooling season, 316–318
airside surface conditions, of outdoor economic analysis, 323–324
coil, 208–209, 208f heating season, 318, 319f
ASHP unit, 204 with frost formation, 313–315, 321–322
compressor suction and discharge without frost formation, 316, 321–322
pressures, 214–215 maintenance costs, 323
conditions of, 206f and operating durations, 318, 318f
effects of, 219–220 proportion of additional first cost, 318,
electronic expansion valve, 214–215 322f
energy analysis, 216–219 ratio of total cost differences, 318, 321f
experimental work, 206–207 system operating durations, 318, 319f
gravity and tube internal resistance, total cost of, 318, 320f
207–208 water-collecting tray
measured tube surface temperatures, additional initial cost effect on total cost,
209–212, 209–210f, 212f 335f, 338–339
practical applications, 205 cooling season, 331–335
refrigerant volumetric flow rate, defrosting stage, 331, 332–333f
214–215, 214f frosting/defrosting cycle, 331, 333f
temperature difference of the outdoor heating seasons with frost formation, 337
coil entrance and exit, 212–214, heating seasons without frost formation,
213–214f 337
trial-and-error manual adjustments, indoor air thermal energy, 337–338
205–207 proportion of additional first cost, 331,
tube internal resistance and gravity, 336f
205–206 proportion of first cost in total cost, 331,
semiempirical mathematical models, 193 335f
tube surface temperature, 193 running cost difference, 338–339
two-circuit and three-circuit outdoor coils, total cost differences, 331, 335f
193
Refrigerant distribution evenness values
(RDEVs), 195 S
Relative humidity (RH), 11 Sensible heat defrosting method, 29–32
Residual water, 57–58 Solar-assisted heat pump, 2–3
Retained melted frost, 139, 140f Solenoid valve (SV), 48
Retained water, 123–124, 124f Surface tension, on uneven defrosting,
Reverse cycle defrosting (RCD), 26–28, 27t, 136–149
115 airside surface conditions of outdoor coil,
defrosting model, 33–34, 33f,34t 140–141, 141–142f
energy, 26–27 ASHP unit, 138
improvements for, 28–34 defrosting duration, 145–146, 146t
airflow and refrigerant distribution energy analysis, 147–149, 147f, 148t
adjustment, 29, 32t experimental cases, 138–139
basic component optimization, 28, 32t experimental conditions, 140t
PCM-TES-based, 29, 30–32t face velocity of outdoor coil, 138, 139f
sensible heat defrosting method, 29–32, fin surface temperatures, 143–145, 144f
32t mass transfer of retained melted frost, 139,
Reynolds numbers, 17–18 140f
Running cost, ASHP unit, 303–305, 310–313 tube surface temperatures, 143–145, 143f