The Effect of Fouling on Low Temperature Heat Exchangers Performance Based on Exergy Analysis

2010 ◽  
Vol 23 (6) ◽  
pp. 1119-1122
Author(s):  
Shuang-Ying Wu ◽  
Xiao-Feng Yuan ◽  
You-Rong Li
Keyword(s):  
Low Temperature ◽  
Heat Exchangers ◽  
Exergy Analysis ◽  
Temperature Heat

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.

Thermodynamic peculiarities of alpha-type Stirling engines for low-temperature difference power generation: Optimisation of operating parameters and heat exchangers using a third-order model

2013 ◽  
Vol 228 (11) ◽  
pp. 1936-1947 ◽  
Author(s):  
Benedikt Hoegel ◽  
Dirk Pons ◽  
Michael Gschwendtner ◽  
Alan Tucker ◽  
Mathieu Sellier
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Temperature Difference ◽  
Heat Exchangers ◽  
Operating Parameters ◽  
Heat Sources ◽  
Third Order ◽  
Concentrated Solar Energy ◽  
Stirling Engines ◽  
Temperature Heat

Low-temperature heat sources such as waste heat and geothermal energy in the range from 100 ℃ to 200 ℃ are widely available and their potential is largely untapped. Stirling engines are one possibility to convert this heat to a usable power output. Much work has been done to optimise Stirling engines for high-temperature heat sources such as external combustion or concentrated solar energy but only little is known about suitable engine layouts at lower temperature differences. With the reduced temperature difference, changes become necessary not only in the heat exchangers and the regenerator but also in the operating parameters such as frequency and phase angle. This paper shows results obtained from a third-order simulation model that help to identify beneficial parameter combinations, and explains the differences of low and high-temperature engines.

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.

Exergy analysis of a low temperature heat pump

Cryogenics ◽  
1983 ◽  
Vol 23 (3) ◽  
pp. 148-150 ◽  
Author(s):  
H.A. Rangrej ◽  
K.G. Narayankhedkar
Keyword(s):  
Low Temperature ◽  
Heat Pump ◽  
Exergy Analysis ◽  
Temperature Heat

Thermodynamic Optimization of Irreversible Power Cycles With Constant External Reservoir Temperatures

1991 ◽  
Vol 113 (4) ◽  
pp. 505-510 ◽  
Author(s):  
L. W. Swanson
Keyword(s):  
Heat Exchanger ◽  
Low Temperature ◽  
Power Output ◽  
Heat Exchangers ◽  
Power Plants ◽  
Cycle Phase ◽  
Change Processes ◽  
Power Cycles ◽  
Global Power ◽  
Temperature Heat

An extended version of the Bejan model of irreversible power plants is proposed using a log-mean temperature difference (LMTD) representation for both the high and low-temperature heat exchangers. The analysis focuses on minimizing the irreversibilities associated with the hot and cold heat exchangers. The results indicate that the maximum power output, external conductance allocation ratio, and second law efficiency are functions of the number total heat exchanger transfer units (N), and are asymptotic to Bejan’s original results as N → O. This asymptote represents a global power output maximum and occurs for either extremely high cycle flow rates or cycle phase change processes in both heat exchangers. The LMTD representation also shows that under optimal conditions, more conductance should be allocated to the low-temperature heat exchanger as N increases.

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