Modeling of a New Structure of Precision Air Conditioning System Using Secondary Condenser for Rh Regulation

Abstract

A dynamic mathematical model for a new structure of precision air conditioning (PAC) has been developed. The proposed PAC uses an additional secondary condenser for relative humidity regulation compared to a basic refrigeration system. The work mechanism for this system and a vapour-compression cycle process of the system are illustrated using psychrometric chart and pressure-enthalpy diagram. A non-linear system model is derived based on the conservation of mass and energy balance principles and then linearized at steady state operating point for developing a 8 th -order state space model suited for multivariable controller design. The quality of linearized model is analyzed in terms of transient response, controllability, observability, and interaction between input-output variables. The developed model is verified through simulation showing its ability for imitating the nonlinear behavior and the interaction of input-output variables. AbstrakPemodelan Sistem Tata Udara Presisi Berstruktur Baru Menggunakan Kondenser Sekunder untuk Pengaturan RH. Tulisan ini membahas penurunan model matematis dinamis untuk sistem tata udara presisi (PAC) dengan struktur baru. Berbeda dengan sistem refrigerasi umumnya, sistem PAC yang diusulkan menggunakan kondenser sekunder tambahan untuk pengaturan kelembaban relatif. Mekanisme kerja dan proses siklus kompresi uap sistem ini diilustrasikan menggunakan psychrometric chart dan diagram tekanan-entalpi. Model nonlinier sistem diturunkan berbasis konservasi massa dan prinsip kesetimbangan energi dan kemudian dilinierisasi pada titik kerja untuk mengembangkan model ruang keadaan orde-8 yang cocok untuk disain pengendali multivariabel. Kualitas model linier dianalisa dari aspek respons transien, kontrolabilitas, observabilitas, dan interaksi antar variabel masukan-keluaran. Model yang dikembangkan diverifikasi secara simulasi menunjukkan kemampuan model untuk meniru karakteristik nonlinier dan interaksi variabel masukan-keluaran.

Model Predictive Control of Precision Air Conditioning System with Secondary Condenser

“…As mentioned before, the model used in the controller design is developed by Subiantoro et al [14]. The schematic representation of the model is shown in Figure 1.…”

“…The dynamic model is derived using energy and mass conservation laws for components composing the PAC system, which includes: compressor model, evaporator model, secondary condenser, and cabinet model. For detail derivation, one can refer to [14]. The developed model is nonlinear.…”

“…where is state variables vector defined as . − is defined in Appendix A of the preliminary work [14].…”

“…The MPC block calculates the optimal control * and uses it to control the plant so that it can follow the setpoint trajectory and fulfil the constraints and cost function criteria. Meanwhile, the plant block is the dynamics model for the controlled process as derived in [14]. It contains system parameters and typically includes uncertainties, both model uncertainty and disturbances.…”

“…: being not able to handle coupled variables in MIMO system, not able to incorporate constraints in control design, and the irksomely need of retuning controller parameters), the new method of controller was proposed. This paper presents MPC controller design based on the previously developed model by Subiantoro et al [14]. The PAC system model is derived using psychrometric data and underlying physics laws, i.e.…”