Transient Performance of Fixed-Bed Regenerators for Energy Recovery in Building Applications

2020 ◽  
Author(s):  
Hadi Ramin ◽  
Easwaran N. Krishnan ◽  
Gurubalan Annadurai ◽  
Carey J. Simonson
Keyword(s):  
Steady State ◽  
Fixed Bed ◽  
Performance Testing ◽  
State Condition ◽  
Test Facility ◽  
Small Scale ◽  
Outlet Temperature ◽  
Quasi Steady State ◽  
Steady State Condition ◽  
Steady State Operation

Abstract A small-scale test facility is developed to determine the sensible effectiveness of a Fixed-Bed Regenerator (FBR) and the results are used to validate a numerical model. The numerical and experimental results for quasi-steady-state conditions are in a good agreement within the experimental uncertainty bounds. At quasi-steady-state condition, the outlet temperature of FBR varies with time but cyclically repeats itself; this is an important difference between FBR (regenerator) and recuperator heat exchangers. The outlet temperature of recuperator heat exchangers reaches a constant value during the steady-state operation. The quasi-steady-state temperature profile is used to determine the sensible effectiveness of FBRs. However, FBRs undergo several cycles to reach the quasi-steady-state condition. The prediction of the duration of the transient duration of FBR is important for performance testing that could save money and time. CSA (Canadian Standards Association) recommends operating FBR for at least one hour to achieve a quasi-steady-state condition. This paper addresses the heat transfer behavior of FBRs during their transient operation. The initial transient cycles depend on the cycle period of FBR, air flow rate and the thermal condition of the exchanger at the beginning of the test. The small-scale FBR test facility is used to study the transient behavior of FBRs and this is the main focus of this paper. The temperature profile during the transient condition of FBR is obtained and the results are compared with the numerical model. The effects of the mass flow rate of air and the cycle duration on the transient period of FBR are studied. The results show that FBR reaches a quasi-steady state operation in less than 30 minutes. The results will be useful for understanding the time required for performance testing, which will reduce the cost and time of each test.

scholarly journals Thermal Stress Analysis of Absorber Tube for a Parabolic Collector under Quasi-Steady State Condition

2015 ◽  
Vol 69 ◽  
pp. 3-13 ◽  
Author(s):  
M.H. Abedini-Sanigy ◽  
F. Ahmadi ◽  
E. Goshtasbirad ◽  
M. Yaghoubi
Keyword(s):  
Thermal Stress ◽  
Steady State ◽  
Stress Analysis ◽  
State Condition ◽  
Quasi Steady State ◽  
Steady State Condition ◽  
Thermal Stress Analysis ◽  
Parabolic Collector

Computer simulation of gas generation and transport in landfills—I: quasi-steady-state condition

2002 ◽  
Vol 57 (13) ◽  
pp. 2475-2501 ◽  
Author(s):  
Mehrdad Hashemi ◽  
Halil I. Kavak ◽  
Theodore T. Tsotsis ◽  
Muhammad Sahimi
Keyword(s):  
Computer Simulation ◽  
Steady State ◽  
State Condition ◽  
Quasi Steady State ◽  
Gas Generation ◽  
Steady State Condition

A Scaling Analysis of a CANDU-6 Moderator Tank Scaled-Down Test Facility

2013 ◽  
Author(s):  
Bo W. Rhee ◽  
H. T. Kim ◽  
S. K. Park ◽  
J. E. Cha ◽  
H.-L. Choi
Keyword(s):  
Steady State ◽  
Boundary Conditions ◽  
Power Supply ◽  
State Condition ◽  
Normal Operation ◽  
Source Distribution ◽  
Test Facility ◽  
Dimensionless Numbers ◽  
Steady State Condition ◽  
Scale Down

Several studies have been performed to derive a set of scaling criteria which were thought to be suitable for reproducing thermal-hydraulic phenomena in a scale-down CANDU moderator tank similar to that in a prototype power plant during a full power steady state condition[1,2]. The major variables of interests are moderator flow circulation and temperature inside the moderator tank during a steady state condition. The key phenomena involved include the inlet jet development and impingement, buoyancy force driven by the moderator temperature difference caused by non-uniform heating, and the viscous friction of the flow across the calandria tube array. In these studies, the governing equations were initially transformed into dimensionless equations based on the representative characteristic values of the basic design such as the time, tank diameter, inlet fluid velocity, and average temperature rise, and 3 dimensionless numbers, Re, Pr, Ar, were identified as those characterizing the key phenomena of the system. The relevant boundary conditions were then identified in a dimensionless form, and the compatibility of keeping these 3 dimensionless numbers, the volumetric heat source distribution, and the boundary conditions in dimensionless forms the same for both the prototype and scale-down tanks were examined, and some of them that are less important are relaxed so as to find a practically implementable set of constraints. The size of the scaled-down moderator tank and corresponding inlet velocity is then found for the available power supply size. As an example, an analysis was performed for a power supply capacity of 500 kW as compared to 100MW for the prototype. As a way to confirm the validity of the current work two numerical CFD simulations were carried out with the boundary conditions at the inlet and outlet ports, and on the walls of the solid structures, such as the moderator tank and calandria tubes, which were derived from those of the dimensionless scales to check if the moderator flow and temperature patterns of both the prototype reactor and scaled-down facilities are identical or at least similar. A steady-state solution is first obtained for the candu-6 reactor normal operation. Similar simulation was done for the scaled-down facility and results presented. Comparison results are discussed, and the cause of the potential distortion of the scaling owing to practical limitations and possible solutions is finally discussed.

TRANSIENT OPERATION OF SENSIBLE FIXED-BED REGENERATORS

2022 ◽  
pp. 1-16
Author(s):  
Hadi Ramin ◽  
Easwaran N Krishnan ◽  
Gurubalan Annadurai ◽  
Carey J. Simonson
Keyword(s):  
Steady State ◽  
Fixed Bed ◽  
Operating Conditions ◽  
Design Parameters ◽  
Transient Temperature ◽  
Quasi Steady State ◽  
Transient Operation ◽  
Steady State Condition ◽  
Test Standards ◽  
Wide Range

Abstract Fixed-bed regenerator is a type of air-to-air energy exchanger and recently introduced for energy recovery application in HVAC systems because of their high heat transfer effectiveness. Testing of FBRs is essential for performance evaluation and product development. ASHRAE and CSA recently included guidelines for testing of FBRs in their respective test standards. The experiments on FBRs are challenging as they never attain a steady state condition, rather undergoes a quasi-steady state operation. Before reaching the quasi-steady state, FBRs undergo several transient cycles. Hence, the test standards recommend getting measurements after one hour of operation, assuming FBR attains the quasi-steady state regardless of test conditions. However, the exact duration of the initial transient cycles is unknown and not yet studied so far. Hence, in this paper, the duration of FBR's transient operation is investigated for a wide range of design and operating conditions. The test standards' recommendation for the transient duration is also verified. The major contributions of this paper are (i) quantifying the effect of design parameters (NTUo and Cr*) on the duration of transient operation and (ii) investigation of the effect of sensor time constant on the transient temperature measurements. The results will be useful to predict and understand the transient behavior of FBRs accurately.

Continuous determination of the volume of a space in a non steady state condition

1974 ◽  
Vol 36 (1) ◽  
pp. 59-66
Author(s):  
Oscar A. Gómez-Poviña ◽  
Carmen Sainz de Calatroni ◽  
Susana Orden de Puhl ◽  
Mariano J. Guerrero
Keyword(s):  
Steady State ◽  
State Condition ◽  
Steady State Condition ◽  
Continuous Determination

An Approach for Snaky Well Productivity under Steady-State Condition

2006 ◽  
Author(s):  
Zhilin Qi ◽  
Zhimin Du ◽  
Baosheng Liang ◽  
Yong Tang ◽  
Shouping Wang ◽  
...  
Keyword(s):  
Steady State ◽  
State Condition ◽  
Well Productivity ◽  
Steady State Condition

Numerical and particle image velocimetry characterizations of flow structures under steady state condition

2013 ◽  
Vol 10 (3) ◽  
pp. 229-244
Author(s):  
Saud Binjuwair ◽  
Salah Ibrahim ◽  
Graham Wigley ◽  
Graham Pitcher
Keyword(s):  
Particle Image Velocimetry ◽  
Steady State ◽  
Particle Image ◽  
State Condition ◽  
Flow Structures ◽  
Steady State Condition ◽  
Image Velocimetry

scholarly journals Prediction of critical heat flux for narrow rectangular channels in a steady state condition using machine learning

2020 ◽  
Author(s):  
Huiyung Kim ◽  
Jeongmin Moon ◽  
Dongjin Hong ◽  
Euiyoung Cha ◽  
Byongjo Yun
Keyword(s):  
Machine Learning ◽  
Heat Flux ◽  
Steady State ◽  
Critical Heat Flux ◽  
State Condition ◽  
Steady State Condition ◽  
Rectangular Channels
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