![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
We propose a novel model control with dynamic adaptation to improve the control accuracy and speed of heat exchangers. The proposed method first applies an accurate mathematical model of heat exchanger as a motion model to create the inverse problem algorithm of manipulated variable. Subsequently, it improves the transient performance using a dynamic adaption of manipulated variable. Compared the control performance to feedback control method, the dynamic adaptation of manipulated variable fed in an exponential function resulted in both approximately a 100% reduction in overshoot and settling time elimination in response to inlet temperature and flow rate disturbances of objective fluid.
Nomenclature
| A | = | heat exchange area (m2) |
| cp | = | specific heat at constant pressure of the fluid (J/kg/K) |
| G | = | mass flow rate (kg/s) |
| h | = | convective heat transfer coefficient for fluids (W/m2/K) |
| H(s) | = | transfer function of outlet parameter |
| K | = | coefficient |
| KD | = | the differential coefficient |
| KI | = | the integral coefficient |
| KP | = | the proportional coefficient |
| m(s) | = | variations of mass flow rate in the complex domain |
| Mp | = | maximum overshoot |
| qv | = | volume flow rate (m3/s) |
| Q | = | heat transfer rate (W) |
| t | = | temperature (°C) |
| tp | = | qualitative temperature of fluids (°C) |
| = | average settling time (s) | |
| T | = | time constant (s) |
| Ts | = | the sample period (s) |
| U | = | the total heat transfer coefficient (W/m2/K) |
| = | output temperature response in the complex domain | |
| λ | = | thermal conductivity (W/m/K) |
| ν | = | kinematic viscosity (m2/s) |
| ξ | = | damp ratio |
| ρ | = | density of fluid (kg/m3) |
| τ | = | time, time constant, or delay time (s) |
| Superscripts | = | |
| = | the assumed value | |
| Subscripts | = | |
| c | = | cold fluid |
| h | = | hot fluid |
| lm | = | log-mean |
| out | = | outlet |
| 0 | = | the initial condition |
| 1 | = | the objective fluid |
| 2 | = | the assistance fluid |
Nomenclature
| A | = | heat exchange area (m2) |
| cp | = | specific heat at constant pressure of the fluid (J/kg/K) |
| G | = | mass flow rate (kg/s) |
| h | = | convective heat transfer coefficient for fluids (W/m2/K) |
| H(s) | = | transfer function of outlet parameter |
| K | = | coefficient |
| KD | = | the differential coefficient |
| KI | = | the integral coefficient |
| KP | = | the proportional coefficient |
| m(s) | = | variations of mass flow rate in the complex domain |
| Mp | = | maximum overshoot |
| qv | = | volume flow rate (m3/s) |
| Q | = | heat transfer rate (W) |
| t | = | temperature (°C) |
| tp | = | qualitative temperature of fluids (°C) |
| = | average settling time (s) | |
| T | = | time constant (s) |
| Ts | = | the sample period (s) |
| U | = | the total heat transfer coefficient (W/m2/K) |
| = | output temperature response in the complex domain | |
| λ | = | thermal conductivity (W/m/K) |
| ν | = | kinematic viscosity (m2/s) |
| ξ | = | damp ratio |
| ρ | = | density of fluid (kg/m3) |
| τ | = | time, time constant, or delay time (s) |
| Superscripts | = | |
| = | the assumed value | |
| Subscripts | = | |
| c | = | cold fluid |
| h | = | hot fluid |
| lm | = | log-mean |
| out | = | outlet |
| 0 | = | the initial condition |
| 1 | = | the objective fluid |
| 2 | = | the assistance fluid |