EXERGY TRANSFER CHARACTERISTICS ON LOW TEMPERATURE HEAT EXCHANGERS

2007 ◽  
Vol 21 (18n19) ◽  
pp. 3503-3505 ◽  
Author(s):  
S. Y. WU ◽  
X. F. YUAN ◽  
Y. R. Li ◽  
L. PENG
Keyword(s):  
Heat Transfer ◽  
Heat Capacity ◽  
Low Temperature ◽  
Transfer Coefficient ◽  
Heat Exchangers ◽  
Cross Flow ◽  
Counter Flow ◽  
Temperature Heat ◽  
Relevant Variables ◽  
Exergy Transfer

By analyzing exergy transfer process of the low temperature heat exchangers operating below the surrounding temperature, the concept of exergy transfer coefficient is put forward and the expressions which involving relevant variables for the exergy transfer coefficient, the heat transfer units number and the ratio of cold to hot fluids heat capacity rate, etc. are derived. Taking the parallel flow, counter flow and cross flow low temperature heat exchangers as examples, the numerical results of exergy transfer coefficient are given and the comparison of exergy transfer coefficient with heat transfer coefficient is analyzed.

Exergy Transfer Effectiveness on Heat Exchanger

2006 ◽  
Author(s):  
Shuang-Ying Wu ◽  
Xiao-Feng Yuan ◽  
You-Rong Li ◽  
Wen-Zhi Cui ◽  
Liao Quan
Keyword(s):  
Heat Transfer ◽  
Heat Capacity ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Cross Flow ◽  
Counter Flow ◽  
Temperature Heat ◽  
Relevant Variables ◽  
Flow Heat ◽  
Exergy Transfer

In this paper, the concept of exergy transfer effectiveness is put forward firstly and the expressions involving relevant variables for the exergy transfer effectiveness, the heat transfer units number and the ratio of cold and hot fluids heat capacity rate have been derived for the high and low temperature heat exchangers. Taking the parallel flow, counter flow and cross flow heat exchangers as examples, the numerical results of exergy transfer effectiveness are given and the comparison of exergy transfer effectiveness with heat transfer effectiveness is analyzed.

THE ANALYSIS OF EXERGY EFFICIENCY IN THE LOW TEMPERATURE HEAT EXCHANGER

2007 ◽  
Vol 21 (18n19) ◽  
pp. 3497-3499 ◽  
Author(s):  
LAN PENG ◽  
YOU-RONG LI ◽  
SHUANG-YING WU ◽  
BO LAN
Keyword(s):  
Heat Transfer ◽  
Heat Capacity ◽  
Heat Exchanger ◽  
Low Temperature ◽  
Transfer Process ◽  
Heat Exchangers ◽  
Heat Transfer Process ◽  
Exergy Efficiency ◽  
Capacity Ratio ◽  
Temperature Heat

Based on the analyzing of the thermodynamic performance of the heat transfer process in the low temperature heat exchangers, the exergy efficiency of the heat transfer process is defined and a general expression for the exergy efficiency is derived, which can be used to discuss the effect of heat transfer units number and heat capacity ratio of fluids on the exergy efficiency of the low temperature heat exchanger. The variation of the exergy efficiency for several kinds of flow patterns in the low heat exchangers is compared and the calculating method of the optimal values of heat capacity ratio for the maximum exergy efficiency is given.

EXERGO-ECONOMIC PERFORMANCE EVALUATION ON LOW TEMPERATURE HEAT EXCHANGER

2005 ◽  
Vol 19 (01n03) ◽  
pp. 517-519 ◽  
Author(s):  
S. Y. WU ◽  
Y. R. LI ◽  
D. L. ZENG
Keyword(s):  
Heat Exchanger ◽  
Low Temperature ◽  
Economic Performance ◽  
Heat Exchangers ◽  
Cross Flow ◽  
Counter Flow ◽  
Flow Process ◽  
Economic Criterion ◽  
Net Profit ◽  
Temperature Heat

Based on the exergo-economic analysis of low temperature heat exchanger heat transfer and flow process, a new exergo-economic criterion which is defined as the net profit per unit heat flux for cryogenic exergy recovery low temperature heat exchangers is put forward. The application of criterion is illustrated by the evaluation of down-flow, counter-flow and cross-flow low temperature heat exchangers performance.

scholarly journals Analysis and Comparison of Some Low-Temperature Heat Sources for Heat Pumps

Energies ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1853 ◽  
Author(s):  
Pavel Neuberger ◽  
Radomír Adamovský
Keyword(s):  
Heat Transfer ◽  
Low Temperature ◽  
Heat Source ◽  
Heat Pump ◽  
Heat Exchangers ◽  
Ambient Air ◽  
Heat Transfer Fluid ◽  
Heat Sources ◽  
Ground Heat Exchangers ◽  
Temperature Heat

The efficiency of a heat pump energy system is significantly influenced by its low-temperature heat source. This paper presents the results of operational monitoring, analysis and comparison of heat transfer fluid temperatures, outputs and extracted energies at the most widely used low temperature heat sources within 218 days of a heating period. The monitoring involved horizontal ground heat exchangers (HGHEs) of linear and Slinky type, vertical ground heat exchangers (VGHEs) with single and double U-tube exchanger as well as the ambient air. The results of the verification indicated that it was not possible to specify clearly the most advantageous low-temperature heat source that meets the requirements of the efficiency of the heat pump operation. The highest average heat transfer fluid temperatures were achieved at linear HGHE (8.13 ± 4.50 °C) and double U-tube VGHE (8.13 ± 3.12 °C). The highest average specific heat output 59.97 ± 41.80 W/m2 and specific energy extracted from the ground mass 2723.40 ± 1785.58 kJ/m2·day were recorded at single U-tube VGHE. The lowest thermal resistance value of 0.07 K·m2/W, specifying the efficiency of the heat transfer process between the ground mass and the heat transfer fluid, was monitored at linear HGHE. The use of ambient air as a low-temperature heat pump source was considered to be the least advantageous in terms of its temperature parameters.

Determination of Heat Transfer Characteristics of Solar Thermal Collectors as Heat Source for a Residential Heat Pump

2015 ◽  
Author(s):  
Maarten G. Sourbron ◽  
Nesrin Ozalp
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Low Temperature ◽  
Heat Source ◽  
Transfer Coefficient ◽  
Heat Pump ◽  
Solar Collector ◽  
Solar Thermal ◽  
Heat Transfer Characteristics ◽  
Temperature Heat

One of the best ways of making efficient use of energy in residential units is to use heat pump. Heat pump performance can be further enhanced by integrating a solar thermal unit to provide hot water and subsidize space heating. This paper presents numerically examined energy feasibility study of a solar driven heat pump system for a low energy residence, where a flat plate solar collector served as the sole low temperature heat source. A parametric study on the ambient-to-solar fluid heat transfer coefficient has been conducted to determine the required solar collector heat transfer characteristics in this system. Solar collector area and storage tank volume were varied to investigate their impact on the system performance. A new performance indicator availability was defined to assess the contribution of the solar collector as low temperature energy source of the heat pump. Results showed that the use of a solar collector as low temperature heat source was feasible if its heat transfer rate (UA-value) was 200 W/K or higher. Achievement of this value with a realistic solar collector area (A-value) required an increase of the overall ambient-to-solar fluid heat transfer coefficient (U-value) with a factor of 6 to 8 compared to the base case with only natural convection heat exchange between solar collector cover and ambient.

Heat Transfer Enhancement Analysis of Al2O3-Water Nanofluid Through Parallel and Counter Flow in Shell and Tube Heat Exchangers

2017 ◽  
Vol 16 (05n06) ◽  
pp. 1750020 ◽  
Author(s):  
S. Nallusamy ◽  
N. Manikanda Prabu
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
Mass Flow ◽  
Flow Rate ◽  
Heat Exchangers ◽  
Counter Flow ◽  
Overall Heat Transfer Coefficient ◽  
Shell And Tube

Heat exchanger plays an essential part in industrial sector in transferring the heat energy. Heat is exchanged between fluids in convection and conduction mode through the walls of the heat exchanger. If the heat transfer medium has low thermal conductivity, it will greatly limit the efficiency of the heat exchanger. Whenever the system acts subjected to an increase in the heat load, heat fluxes caused by more power and smaller size, cooling is one of the technical challenges faced by the industries. The objective of this research work is to evaluate the overall heat transfer coefficient through an experimental analysis on the convective heat transfer and flow characteristics of a nanofluid. In our experiment, the nanofluid consists of water and one percentage volume concentration of Al2O3-water nanofluid flowing through parallel and counter flow in shell and tube heat exchangers. About 50[Formula: see text]nm diameter of Al2O3 nanoparticles was used in this analysis and found that the overall heat transfer coefficient and convective heat transfer coefficient of nanofluid were slightly higher than those of the base liquid at same mass flow rate and inlet temperature. Here, there are three samples of dissimilar mass flow rates, which have been identified for conducting the experiments and their results are continuously monitored and reported. Finally, the observed results through an experimental investigation were presented and concluded that the enhancement of overall heat transfer coefficient is likely to be feasible by means of increasing the mass flow rate of base fluid and prepared nanofluid on the proportional basis.

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