scholarly journals Impact of a Medium Flow Maldistribution on a Cross-Flow Heat Exchanger Performance

10.5772/33111 ◽  
2012 ◽  
Author(s):  
Tomasz Bury
Keyword(s):  
Heat Exchanger ◽  
Cross Flow ◽  
Medium Flow ◽  
Flow Heat ◽  
Flow Maldistribution

Heat and Mass Transfer to Air in a Cross Flow Heat Exchanger with Surface Deluge Cooling

2016 ◽  
Vol 24 (01) ◽  
pp. 1650002 ◽  
Author(s):  
Andrea Diani ◽  
Luisa Rossetto ◽  
Roberto Dall’Olio ◽  
Daniele De Zen ◽  
Filippo Masetto
Keyword(s):  
Heat Exchanger ◽  
Heat Flow ◽  
Flow Rate ◽  
Data Center ◽  
Heat Dissipation ◽  
Cross Flow ◽  
Critical Conditions ◽  
Heat Flow Rate ◽  
External Temperature ◽  
Flow Heat

Cross flow heat exchangers, when applied to cool data center rooms, use external air (process air) to cool the air stream coming from the data center room (primary air). However, an air–air heat exchanger is not enough to cope with extreme high heat loads in critical conditions (high external temperature). Therefore, water can be sprayed in the process air to increase the heat dissipation capability (wet mode). Water evaporates, and the heat flow rate is transferred to the process air as sensible and latent heat. This paper proposes an analytical approach to predict the behavior of a cross flow heat exchanger in wet mode. The theoretical results are then compared to experimental tests carried out on a real machine in wet mode conditions. Comparisons are given in terms of calculated versus experimental heat flow rate and evaporated water mass flow rate, showing a good match between theoretical and experimental values.

Minimum Irreversibility Criteria for Heat Exchanger Configurations

1999 ◽  
Vol 121 (4) ◽  
pp. 241-246 ◽  
Author(s):  
F. E. M. Saboya ◽  
C. E. S. M. da Costa
Keyword(s):  
Heat Capacity ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Cross Flow ◽  
Second Law Of Thermodynamics ◽  
The Other ◽  
Maximum Heat ◽  
Transfer Rates ◽  
Mass Flow Rates ◽  
Flow Heat

From the second law of thermodynamics, the concepts of irreversibility, entropy generation, and availability are applied to counterflow, parallel-flow, and cross-flow heat exchangers. In the case of the Cross-flow configuration, there are four types of heat exchangers: I) both fluids unmixed, 2) both fluids mixed, 3) fluid of maximum heat capacity rate mixed and the other unmixed, 4) fluid of minimum heat capacity rate mixed and the other unmixed. In the analysis, the heat exchangers are assumed to have a negligible pressure drop irreversibility. The Counterflow heat exchanger is compared with the other five heat exchanger types and the comparison will indicate which one has the minimum irreversibility rate. In this comparison, only the exit temperatures and the heat transfer rates of the heat exchangers are different. The other conditions (inlet temperatures, mass flow rates, number of transfer units) and the working fluids are the same in the heat exchangers.

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