Thermodynamic Analysis of Different CO2 Cascade Refrigeration Cycles

DOI

10.2991/iceesd-18.2018.227How to use a DOI?

Keywords

cascade refrigeration cycle; CO2; thermodynamic analysis; coefficient of performance

Abstract

For determining the reasonable ratio of spacing to diameter of double tunnels, the criterion is often only for the excavation, and does not take into account the earthquake situation. In order to ensure the stability of surrounding rock masses, safety and economic rationality during construction and operation of the adjacent tunnels, in this paper, the dynamic responses with different spacing under different earthquake actions and different constitutive relations are analyzed. Based on the plastic zone of the inter-tunnel rock mass connecting or not and the inflection point of the relative displacement curve of the key points of the surrounding rock mass of the tunnel, the reasonable ratio of spacing to diameter under earthquake action is preliminarily determined. The results show that the influence of the earthquake on single tunnel is smaller than that on double tunnels, regardless of the distance between the tunnels and the diameter of the tunnel. Under Five different (NH3/CO2, R22/CO2, R32/CO2, R290/CO2, R404a/CO2) cascade refrigeration cycles are analyzed. It shows that at given condition, the NH3/CO2 cycle has the maximum COP, the COP of R32/CO2 cycle and R290/CO2 cycle is almost the same, the COP of five different cascade refrigeration cycles increased with the evaporating temperatures t1 rise, while it decreased with the heat-transfer temperature difference of condenser-evaporator ?"t and condensing temperature of LTC t3 rise, and different cascade refrigeration cycles except R404a/CO2 cycle have a best COP with the condensing temperature t7 rise, the R404a/CO2 cycle has the minimum COP when the condensing temperature t7 is less than -10?"?, but it almost have the same COP as NH3/CO2 cycle when condensing temperature t7 is 0?"?.

Copyright

© 2018, the Authors. Published by Atlantis Press.

Open Access

This is an open access article distributed under the CC BY-NC license (http://creativecommons.org/licenses/by-nc/4.0/).

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TY  - CONF
AU  - Yingfu Liu
AU  - Yingzheng Rong
AU  - Guangya Jin
PY  - 2018/05
DA  - 2018/05
TI  - Thermodynamic Analysis of Different CO2 Cascade Refrigeration Cycles
BT  - Proceedings of the 2018 7th International Conference on Energy, Environment and Sustainable Development (ICEESD 2018)
PB  - Atlantis Press
SP  - 1230
EP  - 1234
SN  - 2352-5401
UR  - https://doi.org/10.2991/iceesd-18.2018.227
DO  - 10.2991/iceesd-18.2018.227
ID  - Liu2018/05
ER  -