IEA Solar Heating and Cooling Programm - NachhaltigWirtschaften.at
IEA Solar Heating and Cooling Programm - NachhaltigWirtschaften.at IEA Solar Heating and Cooling Programm - NachhaltigWirtschaften.at
IEA SHC Task 38 Solar Air Conditioning and Refrigeration Subtask A Report, November 2009 containers from buoying upwards once they are frozen. Fig. 16 shows a schematic diagram of an encapsulated ice storage system. Fig. 16: Schematic diagram of an encapsulated ice storage system During the charging process the plastic containers are floating in the heat transfer medium (e.g. water/glycol mixture) which has a temperature between −3 °C and −6 °C. The ice grows from the inside of the plastic container walls to their centre. During the discharging process the ice inside the plastic containers starts to melt, at first at the container walls. Once the ice is completely detached from the container wall the heat transfer rate decreases since there is no direct contact between ice and plastic container wall anymore (Fig. 17). Because of this effect the discharging rate decreases and the discharging temperature increases. Fig. 17: Solidification and melting processes in a plastic container during charging and discharging of an encapsulated ice system 5.2.1.3 Sheet Ice Harvester System A sheet ice harvester system (SIHS), shown in Fig. 18, generates the ice outside of the storage tank. Water extracted from the bottom of the storage tank is sprayed over evaporator plates. An additional recirculation circuit is needed. A thin ice layer is formed at page 38
IEA SHC Task 38 Solar Air Conditioning and Refrigeration Subtask A Report, November 2009 the evaporator plates. Once a thickness between 6 mm and 10 mm is reached the ice is removed by a mechanical process if the evaporator consists of tubes or by a periodical injection of hot gas into the evaporator plates. The ice falls into the storage tank below the ice generator. Water flows through this tank and the system is discharged in the same way as an external melt ice-on-coil system. Likewise, low and constant discharging temperatures can be achieved. Water is sprayed over the crushed ice to guarantee a sufficient wetting of the ice. Due to this and the large surface of the small ice particles high discharging rates are achievable. Compared to ice-on-coil systems the necessary heat transfer area needed is small, since the ice is directly generated at the evaporator of the chiller at a very low temperature level. The disadvantage of this system is the high complexity of controlling the SIHS due to the third recirculation circuit and the complicated process of evaluating the charging condition. Since hot gases are injected into the ice generation process, the overall efficiency is lowered. Fig. 18: Schematic diagram of a sheet ice harvester system 5.2.1.4 Ice Slurry Systems Ice slurry is a non-Newtonian fluid (Bingham fluid) which consists of ice crystals in an aqueous solution. The main advantage of ice slurry systems is the high specific energy content due to the latent stored heat. Ice slurries are pumpable up to an ice content of about 40%. These systems can be used within a wide temperature range. The ice content can be influenced by the use of additives. The heat transfer within the machinery is very good since the heat transfer between the fluid and the ice particles is very high and thereby ensures a fast phase change. The working principle of an ice slurry system is shown in Fig. 19. page 39
- Page 23 and 24: Endbericht Solare Kühlung und Klim
- Page 25 and 26: Endbericht Solare Kühlung und Klim
- Page 27 and 28: Endbericht Solare Kühlung und Klim
- Page 29 and 30: Endbericht Solare Kühlung und Klim
- Page 31 and 32: Endbericht Solare Kühlung und Klim
- Page 33 and 34: Endbericht Solare Kühlung und Klim
- Page 35 and 36: Endbericht Solare Kühlung und Klim
- Page 37 and 38: Task 38 Solar Air-Conditioning and
- Page 39 and 40: IEA SHC Task 38 Solar Air Condition
- Page 41 and 42: IEA SHC Task 38 Solar Air Condition
- Page 43 and 44: IEA SHC Task 38 Solar Air Condition
- Page 45 and 46: IEA SHC Task 38 Solar Air Condition
- Page 47 and 48: IEA SHC Task 38 Solar Air Condition
- Page 49 and 50: IEA SHC Task 38 Solar Air Condition
- Page 51 and 52: IEA SHC Task 38 Solar Air Condition
- Page 53 and 54: 3.1 Adsorption Systems Table 1: Ads
- Page 55 and 56: IEA SHC Task 38 Solar Air Condition
- Page 57 and 58: IEA SHC Task 38 Solar Air Condition
- Page 59 and 60: IEA SHC Task 38 Solar Air Condition
- Page 61 and 62: 4 Heat Rejection There is a number
- Page 63 and 64: IEA SHC Task 38 Solar Air Condition
- Page 65 and 66: IEA SHC Task 38 Solar Air Condition
- Page 67 and 68: IEA SHC Task 38 Solar Air Condition
- Page 69 and 70: IEA SHC Task 38 Solar Air Condition
- Page 71 and 72: IEA SHC Task 38 Solar Air Condition
- Page 73: IEA SHC Task 38 Solar Air Condition
- Page 77 and 78: IEA SHC Task 38 Solar Air Condition
- Page 79 and 80: IEA SHC Task 38 Solar Air Condition
- Page 81 and 82: Task 38 Solar Air-Conditioning and
- Page 83 and 84: IEA SHC Task 38 Solar Air Condition
- Page 85 and 86: IEA SHC Task 38 Solar Air Condition
- Page 87 and 88: IEA SHC Task 38 Solar Air Condition
- Page 89 and 90: IEA SHC Task 38 Solar Air Condition
- Page 91 and 92: IEA SHC Task 38 Solar Air Condition
- Page 93 and 94: IEA SHC Task 38 Solar Air Condition
- Page 95 and 96: IEA SHC Task 38 Solar Air Condition
- Page 97 and 98: IEA SHC Task 38 Solar Air Condition
- Page 99 and 100: IEA SHC Task 38 Solar Air Condition
- Page 101 and 102: M M IEA SHC Task 38 Solar Air Condi
- Page 103 and 104: M M M IEA SHC Task 38 Solar Air Con
- Page 105 and 106: IEA SHC Task 38 Monitoring Procedur
- Page 107 and 108: Table of tables Table 1 List of ele
- Page 109 and 110: IEA SHC Task 38 Monitoring Procedur
- Page 111 and 112: IEA SHC Task 38 Monitoring Procedur
- Page 113 and 114: IEA SHC Task 38 Monitoring Procedur
- Page 115 and 116: IEA SHC Task 38 Monitoring Procedur
- Page 117 and 118: IEA SHC Task 38 Monitoring Procedur
- Page 119 and 120: IEA SHC Task 38 Monitoring Procedur
- Page 121 and 122: IEA SHC Task 38 Monitoring Procedur
- Page 123 and 124: IEA SHC Task 38 Monitoring Procedur
<strong>IEA</strong> SHC Task 38 <strong>Solar</strong> Air Conditioning <strong>and</strong> Refriger<strong>at</strong>ion Subtask A Report, November 2009<br />
the evapor<strong>at</strong>or pl<strong>at</strong>es. Once a thickness between 6 mm <strong>and</strong> 10 mm is reached the ice is<br />
removed by a mechanical process if the evapor<strong>at</strong>or consists of tubes or by a periodical<br />
injection of hot gas into the evapor<strong>at</strong>or pl<strong>at</strong>es. The ice falls into the storage tank below the<br />
ice gener<strong>at</strong>or. W<strong>at</strong>er flows through this tank <strong>and</strong> the system is discharged in the same way<br />
as an external melt ice-on-coil system. Likewise, low <strong>and</strong> constant discharging temper<strong>at</strong>ures<br />
can be achieved. W<strong>at</strong>er is sprayed over the crushed ice to guarantee a sufficient wetting of<br />
the ice. Due to this <strong>and</strong> the large surface of the small ice particles high discharging r<strong>at</strong>es are<br />
achievable.<br />
Compared to ice-on-coil systems the necessary he<strong>at</strong> transfer area needed is small, since the<br />
ice is directly gener<strong>at</strong>ed <strong>at</strong> the evapor<strong>at</strong>or of the chiller <strong>at</strong> a very low temper<strong>at</strong>ure level. The<br />
disadvantage of this system is the high complexity of controlling the SIHS due to the third<br />
recircul<strong>at</strong>ion circuit <strong>and</strong> the complic<strong>at</strong>ed process of evalu<strong>at</strong>ing the charging condition. Since<br />
hot gases are injected into the ice gener<strong>at</strong>ion process, the overall efficiency is lowered.<br />
Fig. 18: Schem<strong>at</strong>ic diagram of a sheet ice harvester system<br />
5.2.1.4 Ice Slurry Systems<br />
Ice slurry is a non-Newtonian fluid (Bingham fluid) which consists of ice crystals in an<br />
aqueous solution. The main advantage of ice slurry systems is the high specific energy<br />
content due to the l<strong>at</strong>ent stored he<strong>at</strong>. Ice slurries are pumpable up to an ice content of about<br />
40%. These systems can be used within a wide temper<strong>at</strong>ure range. The ice content can be<br />
influenced by the use of additives. The he<strong>at</strong> transfer within the machinery is very good since<br />
the he<strong>at</strong> transfer between the fluid <strong>and</strong> the ice particles is very high <strong>and</strong> thereby ensures a<br />
fast phase change. The working principle of an ice slurry system is shown in Fig. 19.<br />
page 39
Change language