Page 378 - Defrosting for Air Source Heat Pump
P. 378

Index                                                             375

           T                                    outdoor coil airside surface conditions,
           Technoeconomic performances              262–263, 262–263f
             defrosting duration, 303           refrigerant pressure difference, fluctuation
             defrosting efficiency, 303             of, 267f
                                                refrigerant volumetric flow rate, fluctuation
             energy performance improvement, 304
             frosting and defrosting state          of, 266f
                 assumptions, 304               trial-and-error manual adjustments, 260
             hot refrigerant tube and fins, 303  Two semiempirical models, 73–85, 74t
             multicircuit outdoor coil, 303     airside of three-circuit outdoor coil, 73–74,
             novel RCD method, 303–304              73f
             refrigeration adjustment valve,    assumptions and calculation conditions,
                 influence of                       75–76
               cooling assumptions, 312         computational algorithm, 84, 85f
               defrosting assumptions, 311      defrosting process, 74
               defrosting operations, airside surface  development of, 75–85
                  conditions of, 308–309, 308f  energy used from refrigerant, 91–92, 93f
               economic analysis model, 317     experimental validation, 86–90
               economic analysis process, 307   frost melting without water flowing away
               first costs, 312                     from circuit, 79–81, 80f
               flow chart of methodology, 305f  frost melting with water flowing away from
               frosting assumptions, 310            circuit, 81–82
               frosting/defrosting cycle, 306   limitations, 94
               frosting operations, airside surface  mass and energy flows in defrosting
                  conditions of, 307–308, 307f      stages, 80f,84f
               fundamental assumptions, 309     mass of melted frost, 91–92, 93f
               installation of valves and trays, 305–306  melted frost temperatures, 87–90, 87–89f
               performance parameters, 305, 306t  melted water temperature, 91–92, 92f
               refrigerant distribution, 307    model extrapolation, 90–91
               running cost, 313                preheating, 76–79
               swing-type compressor, 305       refrigerant mass flow rate, 90–91, 91f
               three-circuit outdoor coil, 305–306  refrigerant temperature, 90–91, 90f
               and water-collecting tray, 324–340  thermal resistance of refrigerant, 91–92,
               water-collecting trays, 305–306      92f
           Thermal conductivity, 78–79          tube surface temperatures, 86–87, 86f,88f
           Thermal energy storage (TES) system, 28  uses, 94
           Thermal expansion valve (TEV), 28    water-collecting cylinder, 83–84, 85f
           Three-circuit outdoor coil, 116, 119f  water-collecting trays, 73–74, 83–84, 85f
           Time-based defrosting initiation control  water layer vaporizing, 82–83
               strategy, 258, 344–345         Two-stage technique, 22
             DX A/C system, 260–261
             energy supply and, 271f          U
             flow chart of procedure, 261f    Ultrasonic vibration technique, 16–17
             fluctuation of tube surface temperature,  Uneven defrosting, 303, 343
                 264–265f                       for ASHP unit, 95–110
             frost accumulation, 260, 272f        airside of three-circuit outdoor coil, 98,
             indoor coil air temperature difference,  98f
                 fluctuation of, 269f             assumptions, 102–103
             melted frost, fluctuation of, 266f   defrosting durations, 104, 104t
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