Simulation model for complex refrigeration systems based on two-phase fluid network – Part II: Model application

2008 ◽  
Vol 31 (3) ◽  
pp. 500-509 ◽  
Author(s):  
Wenxing Shi ◽  
Shuangquan Shao ◽  
Xianting Li ◽  
Qisen Yan
Keyword(s):  
Simulation Model ◽  
Two Phase ◽  
Model Application ◽  
Fluid Network ◽  
Phase Fluid

INTEGRATED STEADY-STATE AND DYNAMIC SIMULATION OF MULTI-UNIT AIR CONDITIONERS BASED ON TWO-PHASE FLUID NETWORK MODEL

2012 ◽  
Vol 20 (04) ◽  
pp. 1250020 ◽  
Author(s):  
HONGBO XU ◽  
SHUANGQUAN SHAO ◽  
HUIMING ZOU ◽  
CHANGQING TIAN
Keyword(s):  
Steady State ◽  
Simulation Model ◽  
Moving Boundary ◽  
Lumped Parameter Model ◽  
Two Phase ◽  
Air Conditioners ◽  
Fluid Network ◽  
Discharge Temperature ◽  
State Models ◽  
Phase Fluid

An integrated simulation model is developed to investigate the steady-state and dynamic performance of multi-unit air conditioners (MUACs). It is built as two-phase fluid network which is able to describe different systems by incidence matrixes. And the submodels are embedded in the system framework, where the submodels can be either steady-state or dynamic model, distributed parameter or lumped parameter model. For this case, the numerical submodels are employed with moving-boundary models of condenser and evaporator, steady-state models of compressor and electronic expansion valve. The comparison with experimental data shows that it cannot only predict the steady-state performance, but also catch dynamic trends with high accuracy, for example, the differences of evaporating pressure < ± 4%, condensing pressure < ± 3%, compressor discharge temperature < ± 4° C , superheating degree < ± 2° C and subcooling degree < ± 1° C . Therefore, the simulation model is confirmed as an effective tool to analyze the steady and transient characteristics and optimize the design and control algorithm of MUACs.

Establishment and solution of the RNC flow network model

2014 ◽  
Vol 05 (04) ◽  
pp. 1471001
Author(s):  
Liying Sun ◽  
Liang Liu
Keyword(s):  
Natural Circulation ◽  
Cooling Capacity ◽  
Inlet Temperature ◽  
Two Phase ◽  
Fluid Network ◽  
Air Volume ◽  
The Difference ◽  
Coupling Characteristics ◽  
Phase Fluid ◽  
Indoor And Outdoor

Refrigerant natural circulation (RNC) system is a closed loop recycling system which is composed of evaporator, condenser, gas pipe and the liquid pipe. The difference in indoor and outdoor temperatures will lead to the refrigerant phase-change, and the gravity difference caused by different heights of condenser and evaporator will make the low boiling point refrigerants carry on natural circulation to realize the indoor heating or cooling. In order to analyze the effect of changes in the RNC system upon the working conditions of the indoor and outdoor units as well as the function of the indoor unit, this paper describes the incidence relations among the various components of the RNC system, and establishes gas–liquid two-phase fluid network mathematical model by using the method of fluid network; besides utilizing the model, it also conducts simulator investigation of coupling characteristics of the RNC system's refrigeration condition, and makes an analysis of indoor temperature, indoor unit's air volume, the number of indoor units and the indoor unit capacity and other factors' changes on the coupling characteristics of the RNC system. The results show that under refrigeration conditions, the increase in the air volume of a single indoor unit or room temperature will result in an increase in the cooling capacity of its own indoor units, a decrease in the cooling capacity of other indoor units and a reduction in the total cooling capacity of indoor units of the RNC system; however, the decrease in the outdoor units' inlet temperature will lead to a drop in the evaporation temperature of the system and increase in the cooling capacity.

Volume preserving immersed boundary methods for two-phase fluid flows

2011 ◽  
Vol 69 (4) ◽  
pp. 842-858 ◽  
Author(s):  
Yibao Li ◽  
Eunok Jung ◽  
Wanho Lee ◽  
Hyun Geun Lee ◽  
Junseok Kim
Keyword(s):  
Fluid Flows ◽  
Immersed Boundary ◽  
Immersed Boundary Methods ◽  
Two Phase ◽  
Boundary Methods ◽  
Phase Fluid ◽  
Volume Preserving

scholarly journals Picking up the hydrothermal whisper at Ischia Island in the Covid-19 lockdown quiet

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mariarosaria Falanga ◽  
Paola Cusano ◽  
Enza De Lauro ◽  
Simona Petrosino
Keyword(s):  
Pressure Fluctuations ◽  
Hydrothermal Fluids ◽  
Shallow Aquifer ◽  
Two Phase ◽  
Spectral Content ◽  
Ischia Island ◽  
Continuous Noise ◽  
Organ Pipes ◽  
Source Signals ◽  
Phase Fluid

AbstractIn this paper, we analyse the seismic noise at Ischia Island (Italy) with the objective of detecting the hydrothermal source signals taking advantage of the Covid-19 quiescence due to lockdown (strong reduction of anthropogenic noise). We compare the characteristics of the background noise in pre-, during and post-lockdown in terms of spectral content, energy release (RMS) and statistical moments. The continuous noise is decomposed into two independent signals in the 1−2 Hz and 2−4 Hz frequency bands, becoming sharpened around 1 Hz and 3 Hz respectively in lockdown. We propose a conceptual model according to which a dendritic system of fluid-permeated fractures plays as neighbour closed organ pipes, for which the fundamental mode provides the persistent whisper and the first higher mode is activated in concomitance with energy increases. By assuming reasonable values for the sound speed in low vapor–liquid mass fraction for a two-phase fluid and considering temperatures and pressures of the shallow aquifer fed by sea, meteoric and deep hydrothermal fluids, we estimate pipe lengths in the range 200–300 m. In this scheme, Ischia organ-like system can play both continuous whisper and transients, depending on the energy variations sourced by pressure fluctuations in the hydrothermal fluids.

scholarly journals Functional Estimation of Plate Type Evaporator with Communication Wick for Two-Phase Fluid Loop in Space

2006 ◽  
Vol 72 (719) ◽  
pp. 1781-1788
Author(s):  
Haruo KAWASAKI ◽  
Ryoji IMAI ◽  
Kanji OHONISHI ◽  
Kengou OHKUBO ◽  
Terushige FUJII
Keyword(s):  
Two Phase ◽  
Functional Estimation ◽  
Phase Fluid ◽  
Plate Type
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