tailieunhanh - Carbon Materials for Advanced Technologies Part 11

Tham khảo tài liệu 'carbon materials for advanced technologies part 11', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 330 regenerators which also exhibit thermal waves. In order to use the recovered heat it is necessary to transfer it from the cooling bed loop to the heating bed loop. It was proposed to do this with a further gas-to-gas heat exchanger and is denoted by the vertical heat arrow in Fig. 15. Only one phase of the cycle is shown in Fig. 15 in which bed 1 is heated and bed 2 is cooled. The clockwise flow of refrigerant through the bed 1 circuit takes the gas through the pre-heating heat exchanger where heat extracted from bed 2 is added the external heat exchanger where heat from a gas flame is added and into bed 1. The refrigerant gas emerges cold from this bed until the thermal wave starts to break through. In bed 2 the circulation of hot gas from the bed passes through the inter-loop heat exchanger through the external cooler which provides some of the useful output of a heat pump system and back into bed 2. The gas emerging from the bed remains hot until the thermal wave starts to break through at which time it undergoes a rapid drop in temperature. When the two thermal waves start to break through the opposite phase of the cycle begins. Valves are switched which effectively swap the two beds over so that bed 1 is cooled and bed 2 is now heated. The advantages of this concept are 1. The cycle is highly regenerative and hence highly efficient. 2. There is no complex and expensive heat exchanger within each bed. 3. There is no added thermal mass due to the use of heat exchangers. 4. The high heat transfer rate allows rapid cycle times which result in the plant being more compact and less expensive to produce. One disadvantage of the system described is the need for the gas-to-gas heat exchanger required to transfer recovered energy between the fluid loops. As a conventional gas-to-gas heat exchanger it could be both large and expensive and there might be matching problems when the heat rejected by one bed is not required at the same time by the other bed. Critoph and