![Sample our Engineering & Technology journals, sign in here to start your access, latest two full volumes FREE to you for 14 days]({"type":"image" , "src" : "/sda/5933/TOC-Subject-Sample-2021-Engineering-Tech.jpg"})
Abstract
This article describes an experimental facility designed and constructed to measure heat transfer coefficients and frictional pressure drop in a small-diameter horizontal test section with two-phase multi-component zeotropic mixtures at cryogenic temperatures. The aim of this facility is to enable the collection of high-accuracy data to overcome the scarcity of heat transfer and pressure drop data for zeoptropic mixtures undergoing a phase change (boiling). These data can then be used to support model development efforts to characterize the pressure drop and heat transfer process in horizontal tubes. The test facility is intended to provide measurements for a range of test conditions, including varying mixture components, mixture compositions, heat fluxes, mass fluxes, evaporating pressures, and tube diameters. The temperature range associated with the mixture measurements varies from near 150 K to room temperature. The heat transfer coefficient measurements have been shown to be repeatable and accurate with an uncertainty of less than 10%. The pressure drop measurements have been calibrated, and the facility is capable of measuring the frictional pressure drop under both adiabatic and diabatic conditions with an uncertainty of less than 20%.
Nomenclature
| D | = | diameter |
| f | = | friction factor |
| g | = | gravitational acceleration |
| G | = | mass flux |
| h | = | enthalpy |
| htc | = | heat transfer coefficient |
| ID | = | dinner diameter |
| k | = | thermal conductivity |
| K | = | coefficient |
| L | = | length |
| = | mass flow rate | |
| OD | = | outer diameter |
| P | = | pressure |
| = | heat transfer rate | |
| Q″ | = | heat flux |
| R | = | roughness |
| Re | = | Reynolds number |
| T | = | temperature |
| th | = | wall thickness |
| u | = | uncertanty |
| x | = | quality |
| z | = | composition |
Subscripts
| a | = | average |
| A | = | test section approach |
| B | = | actual inlet to active portion of test section |
| co | = | combined |
| C | = | actual outlet of active portion of test section |
| c | = | corrected |
| cal | = | calibration |
| D | = | test section departure |
| d | = | discharge |
| DAQ | = | data acquisition system |
| i | = | instrument |
| in | = | inlet |
| l | = | liquid |
| LMTD | = | logarithmic mean temperature difference |
| out | = | outlet |
| p | = | precision |
| RMS | = | root mean squared |
| s | = | suction |
| ss | = | stainless steel |
| v | = | vapor |
Greek symbols
| α | = | void fraction |
| δ | = | uncertainty |
| Δ | = | difference |
| ρ | = | density |
| σ | = | surface tension |