scholarly journals On the Equality Assumption of Latent and Sensible Heat Energy Transfer Coefficients of the Bowen Ratio Theory for Evapotranspiration Estimations: Another Look at the Potential Causes of Inequalities

Climate ◽  
2014 ◽  
Vol 2 (3) ◽  
pp. 181-205 ◽  
Author(s):  
Suat Irmak ◽  
Ayse Kilic ◽  
Sumantra Chatterjee
Keyword(s):  
Energy Transfer ◽  
Bowen Ratio ◽  
Heat Energy ◽  
Sensible Heat ◽  
Transfer Coefficients

scholarly journals Research on the design and application of capillary heat exchangers for heat pumps in coastal areas

2021 ◽  
Vol 42 (3) ◽  
pp. 333-348
Author(s):  
Zhenpeng Bai ◽  
Yanfeng Li ◽  
Jin Zhang ◽  
Alan Fewkes ◽  
Hua Zhong
Keyword(s):  
Renewable Energy ◽  
Energy Transfer ◽  
Heat Exchanger ◽  
Heat Pump ◽  
Transfer Rate ◽  
Coastal Areas ◽  
Heat Energy ◽  
Low Carbon ◽  
Energy Transfer Rate ◽  
Pump System

This study investigated the optimal design of a capillary heat exchanger device for the heat pump system and its innovative engineering application in a building. The overall aim was to use a capillary heat exchanger to obtain energy in coastal areas for promoting renewable energy in low-carbon building design. Initially, the main factors affecting the efficiency of the capillary heat exchanger were identified, a mathematical model was then established to analyse the heat transfer process. The analysis showed the flow rate and the capillary length are the key factors affecting the efficiency of the capillary heat exchanger. Secondly, to optimize the structural design of the capillary heat exchanger, the heat energy transfer is calculated with different lengths of the capillary under various flow rates in summer and winter conditions, respectively. Thirdly, a typical building is selected to analyse the application of the capillary heat exchanger for extracting energy in the coastal area. The results show the performance of the selected capillary heat exchanger heat pump system, in winter, the heat energy transfer rate is 60 W/m2 when the seawater temperature is 3.7 °C; in summer, the heat energy transfer rate is 150 W/m2 when the seawater temperature is 24.6 °C. Finally, the above field test results were examined using a numerical simulation model, the test and simulation results agree with each other quite well. This paper is conducive in promoting the development of the capillary heat exchanger heat pump as an innovative sustainable technology for net-zero energy and low carbon buildings using renewable energy in coastal areas. Practical application: A recently proposed capillary heat exchanger is used as an energy extraction and utilisation device to obtain energy in coastal areas for promoting renewable energy in low-carbon building design. This paper explores the application of a capillary heat exchanger as both cold and heat sources for application in typical low-rise buildings. The analysis of the heat energy transfer rate of a typical low-rise building located in a coastal area in summer and winter provides guidance for the application of capillary heat exchangers.

Heat Energy Transfer Using Butyl Stearate as Phase Change Material for Free-Cooling Applications

2018 ◽  
Vol 144 (4) ◽  
pp. 04018043 ◽  
Author(s):  
Umair Saleem ◽  
Muhammad Shahzad Aziz ◽  
Adeel Waqas ◽  
Muhammad Adnan Hanif
Keyword(s):  
Energy Transfer ◽  
Phase Change ◽  
Phase Change Material ◽  
Heat Energy ◽  
Free Cooling ◽  
Butyl Stearate ◽  
Change Material

Diffusion Layer Theory for Turbulent Vapor Condensation With Noncondensable Gases

1993 ◽  
Vol 115 (4) ◽  
pp. 998-1003 ◽  
Author(s):  
P. F. Peterson ◽  
V. E. Schrock ◽  
T. Kageyama
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Mass Transfer ◽  
Vapor Condensation ◽  
Sensible Heat ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Noncondensable Gas ◽  
Noncondensable Gases ◽  
Vertical Tubes

In turbulent condensation with noncondensable gas, a thin noncondensable layer accumulates and generates a diffusional resistance to condensation and sensible heat transfer. By expressing the driving potential for mass transfer as a difference in saturation temperatures and using appropriate thermodynamic relationships, here an effective “condensation” thermal conductivity is derived. With this formulation, experimental results for vertical tubes and plates demonstrate that condensation obeys the heat and mass transfer analogy, when condensation and sensible heat transfer are considered simultaneously. The sum of the condensation and sensible heat transfer coefficients becomes infinite at small gas concentrations, and approaches the sensible heat transfer coefficient at large concentrations. The “condensation” thermal conductivity is easily applied to engineering analysis, and the theory further demonstrates that condensation on large vertical surfaces is independent of the surface height.

scholarly journals Comparison in determination of mass-energy transfer coefficients

2018 ◽  
Vol 1044 ◽  
pp. 012015
Author(s):  
G J Teixeira ◽  
C H Souza ◽  
R S Cardoso ◽  
J G P Peixoto
Keyword(s):  
Energy Transfer ◽  
Mass Energy ◽  
Transfer Coefficients

Evaluation of energy transfer coefficients in Tm-doped fibers for fiber lasers

2017 ◽  
Author(s):  
Jakub Cajzl ◽  
Pavel Peterka ◽  
Pavel Honzátko ◽  
Ondřej Podrazký ◽  
Michal Kamrádek ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Fiber Lasers ◽  
Transfer Coefficients ◽  
Doped Fibers

Experimental investigation on the effect of sensible heat energy storage in an inclined solar still with baffles

2018 ◽  
Vol 116 ◽  
pp. 49-56 ◽  
Author(s):  
B. Madhu ◽  
E. Balasubramanian ◽  
A.E. Kabeel ◽  
S.A. El-Agouz ◽  
A. Muthu Manokar ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Energy Storage ◽  
Heat Energy ◽  
Sensible Heat ◽  
Solar Still

scholarly journals Seasonal and inter annual variability of energy exchange above a boreal Scots pine forest

2010 ◽  
Vol 7 (4) ◽  
pp. 6441-6494 ◽  
Author(s):  
S. Launiainen
Keyword(s):  
Heat Flux ◽  
Scots Pine ◽  
Seasonal Cycle ◽  
Sensible Heat Flux ◽  
Bowen Ratio ◽  
Pine Forest ◽  
Surface Conductance ◽  
Sensible Heat ◽  
Annual Variability ◽  
Scots Pine Forest

Abstract. Twelve-years of eddy-covariance measurements conducted above a boreal Scots pine forest in Hyytiälä, Southern Finland, were analyzed to assess the seasonal and inter-annual variability of surface conductance (gs) and energy partitioning. The gs had distinct annual course, driven by the seasonal cycle of the Scots pine. Low gs (2–3 mm s−1 in April) restricted transpiration in springtime and caused the sensible heat flux to peak in May–June while evapotranspiration takes over later in July–August when gs is typically 5–7 mm s−1. Hence, during normal years Bowen ratio decreases from 4–6 in April to 0.7–0.9 in August. Sensitivity of gs to ambient vapor pressure deficit (D) was relatively constant but the reference value at D=1 kPa varied seasonally and between years. Only two drought episodes when volumetric soil moisture content in upper mineral soil decreased below 0.15 m3 m−3 occurred during the period. Below this threshold value transpiration was strongly reduced, which promoted sensible heat exchange increasing Bowen ratio to 3–4. Annual evapotranspiration varied between 218 and 361 mm and accounted between 50% and 90% of equilibrium evaporation. The forest floor contributed between 16 and 25% of the total evapotranspiration on annual scale. The fraction stayed similar over the observed range of environmental conditions including drought. The inter-annual variability of evapotranspiration could not be linked to any mean climate parameter while the summertime sensible heat flux and net radiation were well explained by global radiation. The energy balance closure varied annually between 0.66 and 0.95 and had a distinct seasonal cycle with worse closure in spring when large proportion of available energy is partitioned into sensible heat.

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