Transient behavior of run-around heat and moisture exchanger system. Part IІ: Sensitivity studies for a range of initial conditions

Abstract Part І of this paper [17] developed and verified the numerical model for simultaneous heat and moisture transfer in the run-around membrane energy exchanger (RAMEE) system to determine the transient behavior of the system under different initial and operating conditions. This paper presents the transient response of the RAMEE system for step changes in the inlet supply air temperature and humidity ratio. Also the system quasi-steady state operating conditions are predicted as the system approaches its asymptotic operating condition. The transient responses are predicted with changes in various parameters. These include: the number of heat transfer units, thermal capacity ratio, heat loss/gain ratio, storage volume ratio and the normalized initial salt solution concentration. It is shown that the storage volume ratio and the initial salt solution concentration have significant impacts on the transient response of the system and heat transfer between the RAMEE system and the surrounding environment can change the system quasi-steady conditions substantially.

[1]  Carey J. Simonson,et al.  Relationship between energy wheel speed and effectiveness and its transient response, Part II: Comparison between mathematical model predictions and experimental measurements and uncertainty analysis , 2006 .

[2]  Sunil Sarangi,et al.  Transient Behavior of Crossflow Heat Exchangers With Longitudinal Conduction and Axial Dispersion , 2004 .

[3]  F. E. Romie.  Transient Response of Gas-to-Gas Crossflow Heat Exchangers With Neither Gas Mixed , 1983 .

[4]  Steady-State and Transient Behavior of Two Heat Exchangers Coupled by a Circulating Flowstream , 2005 .

[5]  R. W. Besant,et al.  The design of a run-around heat recovery system , 1988 .

[6]  Haisheng Fan,et al.  Performance of a Run-Around System for HVAC Heat and Moisture Transfer Applications Using Cross-Flow Plate Exchangers Coupled with Aqueous Lithium Bromide , 2006 .

[7]  Giampiero Spiga,et al.  Step response of the crossflow heat exchanger with finite wall capacitance , 1992 .

[8]  P. Heggs,et al.  On the search for new solutions of the single-pass crossflow heat exchanger problem , 1985 .

[9]  Han-Taw Chen,et al.  Simple method for transient response of gas-to-gas cross-flow heat exchangers with neither gas mixed , 1991 .

[10]  Wilfried Roetzel,et al.  Steady-state and transient behaviour of two heat exchangers coupled by a circulating flowstream , 2002 .

[11]  R. A. Mashelkar,et al.  Heat Transfer Equipment Design , 1988 .

[12]  R. Besant,et al.  Transient behavior of run-around heat and moisture exchanger system. Part І: Model formulation and verification , 2009 .

[13]  Carey J. Simonson,et al.  Heat and moisture transfer in energy wheels during sorption, condensation and frosting conditions , 1998 .

[14]  Carey J. Simonson,et al.  Relationship between energy wheel speed and effectiveness and its transient response, Part I: Mathematical development of the characteristic time constants and their relationship with effectiveness , 2006 .