Feasibility study of a two-stage vapour compression heat pump with ammonia-water solution circuits: experimental results

1993 ◽  
Vol 16 (4) ◽  
pp. 258-264 ◽  
Author(s):  
Milind V Rane ◽  
Reinhard Radermacher
1998 ◽  
Vol 120 (1) ◽  
pp. 25-31 ◽  
Author(s):  
J. J. Rizza

An analysis of a low-temperature thermal storage system using an ammonia-water solution both as a refrigerant and as a low-temperature thermal storage material is considered. The thermal storage is useable at a temperature of −27°C and higher. The proposed system is designed to shift electric demand from high to low-demand periods. The system utilizes a heat-operated absorption refrigeration system; however, the generator heat is supplied by a self-contained vapor compression heat pump. The heat pump is operated during the off-peak period to recover the low-temperature thermal storage by reprocessing the stored ammonia-water solution to a lower ammonia-water concentration. The ammonia vapor liberated from solution in the dephlegmator is used in the compressor to produce the generator heat. Three different configurations are considered, including a solar-assisted system. The results are compared to an eutectic salt storage system.


Author(s):  
Lijie Feng ◽  
Zhenghao Jin ◽  
Runfa Zhou ◽  
Mengkai Xu ◽  
Luwen Qin ◽  
...  

2021 ◽  
Vol 12 (5) ◽  
pp. 1-25
Author(s):  
Shengwei Ji ◽  
Chenyang Bu ◽  
Lei Li ◽  
Xindong Wu

Graph edge partitioning, which is essential for the efficiency of distributed graph computation systems, divides a graph into several balanced partitions within a given size to minimize the number of vertices to be cut. Existing graph partitioning models can be classified into two categories: offline and streaming graph partitioning models. The former requires global graph information during the partitioning, which is expensive in terms of time and memory for large-scale graphs. The latter creates partitions based solely on the received graph information. However, the streaming model may result in a lower partitioning quality compared with the offline model. Therefore, this study introduces a Local Graph Edge Partitioning model, which considers only the local information (i.e., a portion of a graph instead of the entire graph) during the partitioning. Considering only the local graph information is meaningful because acquiring complete information for large-scale graphs is expensive. Based on the Local Graph Edge Partitioning model, two local graph edge partitioning algorithms—Two-stage Local Partitioning and Adaptive Local Partitioning—are given. Experimental results obtained on 14 real-world graphs demonstrate that the proposed algorithms outperform rival algorithms in most tested cases. Furthermore, the proposed algorithms are proven to significantly improve the efficiency of the real graph computation system GraphX.


2018 ◽  
Vol 228 ◽  
pp. 1486-1498 ◽  
Author(s):  
Hailong Li ◽  
Pietro Elia Campana ◽  
Yuting Tan ◽  
Jinyue Yan

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