[10]
the temperature TLP of LP port is closely related to circulation flow rate of driven gases. The cooling process of E-1 and compression process of circulation stream couple together to influence on expansion efficiency of WRR. The cooler duty wc equals the exchanging work wex, between driving and driven gases (or circulation gases). FIG. 3 shows a typical result for expansion ratio εe= 0. 65Mpa/0. 15Mpa with or without cooler E-1. The parameters involved are peak temperature TTH, temperature of LP port TLP, expansion efficiency, circulation ratio, and compression efficiency. The pressure difference of LP and LT ports is varied from 5. 0kPa-10. 0kPa which determined by the pressure drops of recirculation operation units like the cooler. The mass flux of driving flow is 1. 0kg/s and the circulation flux can be calculated through thermodynamic analysis. With the cooler open, the expansion efficiency enhances about 10%, and increases with εc decreasing. But with the cooler closed, decreases with εc increasing. With or without cooler, the circulation flux increases with εc increasing. It is follows that one can enhance the refrigeration performance by increasing circulation flux. (a) (b) FIG. 3 Experimental results of performance of WRR. It is also found that, the cooler duty wc is irrelevant to εe and. The exchanging work wex is irrelevant to, but increases with εe increasing. With double area of cooler E-1, there is only slightly changes of and, but large changes of. This means that temperature of LP port has little influence on refrigeration efficiency. The inspiring result of dry gases that TLP has little influence on makes possible of maintaining excellent refrigeration efficiency when WRR operating with high-hydrated gases. To verify this, a series of experiments on WRR has performed. TAB. 3 shows some experimental results of WRR with different liquid fractions. The experiment expansion ratio is hold at 0. 45MPa/0. 15MPa with rotor channel length 400 mm. The driving motor's frequency is hold at 60Hz in optimization frequency zone. For multiphase stream, the refrigeration entropy efficiency is often expressed as function of enthalpy under saturation. But for convenience, this paper use absolutely temperature drop to measure the refrigeration performance for different liquid rate of HP port. TAB. 3 Experimental results of WRR with different liquid fractions. LiqFrac. %w PHP /MPa PHT /MPa PLP /MPa PLT /MPa THP /°C THT /°C TLP /°C TLT /°C /°C.
Google Scholar
712 It is found from experiments that most of glycol solutions drain from HT port and hot bottom side of WRR, which is similar to traditional gas wave refrigerators. For supersaturated or condensate gas streams, the coarse or preliminary separation processes can make full use of gravity by setting vertical arrangement or use of centrifugal forces by changing the export direction of HT port. These experiments also show that the temperature of HT port decreases dramatically with the increase of liquid fraction in gas streams of HP port. The main reason is that, the low temperature of HP and large heat capacity of liquids make lower temperature of driven gases after shockwave. In R718 condensation wave rotor, the flash evaporation of high pressured liquid stream balances the sensible heat of driven gases. The compression ratio remains unchanged, but temperature drop decreases slightly with the increase of. The refrigeration performance remains virtually unchanged when liquid holdup bellows 13. 7 % (w). This shows the excellent operation stability of WRR at high liquid holdup condition. Conclusions In the present study, a number of experiments on axial-flow WRR prototypes by adjusting cooler between HT and LP port have performed. Relations of exchanging work, supercharging and refrigerating performances and circulation flux ratio show that expansion efficiency are affected by the energy exchange between driving and driven flows. The cooler has complicated impact on the compression and expansion efficiencies. A fruitful result that temperature of LP port has little influence on refrigeration efficiency is achieved. This makes possible of maintaining excellent refrigeration efficiency when WRRs operating with high-liquid gases. A series of experiments on compressed air with large amounts of free water have verified this inspiring fact. Acknowledgements This present work was supported by grants from the National Natural Science Foundation of China project Theory Study on R718 Vapor Compression Refrigeration with Phase Transition Wave Rotor, (51106017). References.
Google Scholar
