Yan R.,Shanghai JiaoTong University |
Shi J.-Y.,Shanghai JiaoTong University |
Qing H.,Shanghai JiaoTong University |
Chen J.,Shanghai JiaoTong University |
Song J.,International Copper Association Ltd.
SAE Technical Papers | Year: 2014
Two phase flow mal-distribution in inlet header of the parallel flow evaporator will cause performance degradation, partial frosting and comfortableness problems. In order to solve these issues in heat pump system of electric vehicles, four types of small diameter tube and fin heat exchangers with different flow passage were designed and experimental measured in heat pump system of electric vehicles. The experimental results showed that in terms of performance, the small diameter tube and fin heat exchanger can reach even exceed the micro-channel heat exchanger on capacity and COP in heating model. Compared with micro-channel, the tube and fin heat exchanger with 4 inlets and 4 outlets can increase capacity from 2010W to 2689W, and increase COP from 2.6 to 2.8. However the frost/defrost experimental results showed that there was a decrease on the capacity of micro-channel heat exchanger after several frost/defrost periods. For the small diameter tube and fin heat exchangers, the condensate water was easier to be drained, thus partial pressure difference and heat exchange capacity would recover to the initial value eventually. Therefore small diameter tube and fin heat exchangers possess a good potential in the application used in heat pump of electric vehicles. Copyright © 2014 SAE International.
Chambers A.,University of Ottawa |
Krewski D.,University of Ottawa |
Birkett N.,University of Ottawa |
Plunkett L.,Integrated Biostrategies LLC |
And 11 more authors.
Journal of Toxicology and Environmental Health - Part B: Critical Reviews | Year: 2010
There is a need to define exposure-response curves for both Cu excess and deficiency to assist in determining the acceptable range of oral intake. A comprehensive database has been developed where different health outcomes from elevated and deficient Cu intakes were assigned ordinal severity scores to create common measures of response. A generalized linear model for ordinal data was used to estimate the probability of response associated with dose, duration and severity. The model can account for differences in animal species, the exposure medium (drinking water and feed), age, sex, and solubility. Using this model, an optimal intake level of 2.6 mg Cu/d was determined. This value is higher than the current U.S. recommended dietary intake (RDI; 0.9 mg/d) that protects against toxicity from Cu deficiency. It is also lower than the current tolerable upper intake level (UL; 10 mg/d) that protects against toxicity from Cu excess. Compared to traditional risk assessment approaches, categorical regression can provide risk managers with more information, including a range of intake levels associated with different levels of severity and probability of response. To weigh the relative harms of deficiency and excess, it is important that the results be interpreted along with the available information on the nature of the responses that were assigned to each severity score.
Ding W.K.,Xian Jiaotong University |
Fan J.F.,Xian Jiaotong University |
He Y.L.,Xian Jiaotong University |
Tao W.Q.,Xian Jiaotong University |
And 3 more authors.
Applied Thermal Engineering | Year: 2011
A circuit data structure (circuit connection network) for a general description of different circuit configurations in computer programs is presented. On basis of this data structure, a general tube-by-tube simulation model and the corresponding code for prediction of plate fin-and-tube heat exchanger performance are developed. The code can be applied to any complex circuit configuration, and also has great flexibility in simulation of heat exchanger with different fin structures, tube types, and various refrigerants under both dry and wet conditions. The model and the code are verified against experimental results both in literature and authors' data, and have been successfully adopted to simulate a practical heat exchanger. Design software based on the model is developed using C++, which is a highly flexible and customizable simulation platform with friendly graphic user interface. © 2011 Elsevier Ltd.
Fan J.,Xian Jiaotong University |
Ding W.,Xian Jiaotong University |
Wu Z.,Xian Jiaotong University |
He Y.,Xian Jiaotong University |
And 4 more authors.
Frontiers of Energy and Power Engineering in China | Year: 2011
In this paper, a simple yet efficient performance comparison method is proposed based on the assumptions of constant properties and identical frontal area. For this method, no correlations are required, and a small number of discrete data are sufficient. To illustrate the feasibility of the proposed approach, a new slotted fin with 4 mm tubes is designed to replace the original louvered fin with tubes of 7 mm. The orthogonal design method is adopted in the fin design to reduce the number of computational cases significantly, and yet a nearly optimum combination of major geometric factors can still be obtained. The reasonable parametric combination of 3 global parameters is obtained by analyzing the numerical results of 16 plain plate fins. Based on this result, 3 new slotted fins with different fin pitches are studied. The slotted fin with a fin pitch of 1.4 mm is recommended after considering the heat transfer, comprehensive performance, and cost of material and operation. The result shows that compared with the original louvered fin, the recommended fin not only increases the heat transfer rate by 2.2%, 22.5%, and 13.7% under an identical flow rate, identical pressure drop, and identical pumping power constraint, respectively, but also saves approximately 36% of the copper tube materials. © 2010 Higher Education Press and Springer-Verlag Berlin Heidelberg.