ASSIGNMENT 2
RESEARCH QUESTION
RESEARCH METHODOLOGY
By
Jatnika Setiawan 23123004
MECHANICAL ENGINEERING DEPARTMENT
FACULTY OF MECHANICAL AND AEROSPACE ENGINEERING
INSTITUT TEKNOLOGI BANDUNG
2023
Paper :
Experimental Study of Heat Transfer Characteristics of Supercritical Pressure R134a in a Horizontal Tube
Ran Tian, Dabiao Wang, Yue Zhang, Yuezheng Ma, Hui Li, Lin Shi
1. Resume
The study experimentally investigates the heat transfer characteristics of R134a at supercritical
pressures in a horizontal tube to provide basic heat transfer data and heat transfer correlation. The
influences of the heat flux, mass flux and pressure on the wall temperature and heat transfer
coefficient are analyzed. The results show that in a horizontal tube, the buoyancy effect due to
density variations causes non-uniformity of the wall temperatures in the circumferential direction.
The heat transfer deteriorates along the top surface at high heat flux to mass flux ratio, while heat
transfer along the bottom surface is enhanced at all operating conditions. The pressure mainly
affects the heat transfer coefficient on the bottom surface at small heat flux to mass flux ratio. Nine
heat transfer correlations are evaluated with the results showing that the Dittus Boelter type
correlations with property modifications have acceptable accuracy for the bottom surface but all of
the correlations fail to predict the heat transfer coefficient on the top surface. A new correlation
using a buoyancy parameter to include the buoyancy is then developed. Results show that the new
correlations agree well with the data.
2. What have been done
a. Experiments on R134a flowing in a horizontal tube and supercritical pressure with wide range of
conditions :
din = 10.3 mm
p = 1.02-1.2 pc
G = 400-1500 kg/ms2
q’’ = 20-100 kW/m2
b. New heat transfer correlation using buoyancy parameter to include the buoyancy effect to predict
the top surface heat transfer coefficients
c. Modified Dittus-Boelter type correlation that includes a density ratio to predict the bottom
surface temperature
3. What need to do in the future
Evaluate the correlation for broader range of system and other working fluids such as R1234yf and
R245fa