PDF Publication Title:
Text from PDF Page: 013
Mathematics 2022, 10, 3167 13 of 27 Outer loop Chamber temperature control T ref chamber + Tchamber Refrigerated chamber Tchamber Q ̇ e , s e c Q ̇ r e f Q ̇ T E S sec TES e,sec A v Q ̇ e,sec Q ̇ T ES,sec Q ̇ T ES,sec Cooling power scheduler · Economics · Efficiency · Feasibility Q ̇ r e f Inner loop Cooling power control Q ̇ Q ̇ r e f TES - Outer controller Q ̇ r e f T ES,sec Cooling power control · Efficiency · Operating constraints Av,TES m ̇ T E S , s e c EEV TES-backed-up TES refrigeration cycle TES EEV Condenser Compressor Tank N Tchamber Evaporator Q ̇ R Figure 6. Scheduling and control strategy for the TES-backed-up refrigeration system. Given a certain demand Q ̇ re f , the scheduler is intended to compute the references of the sec three cooling powers involved: Q ̇ re f , Q ̇ re f , and Q ̇ re f , according to efficiency, economic, e,sec TES TES,sec and feasibility criteria. The cooling power controller is then responsible for getting the TES-backed-up refrigeration system to actually provide the three required cooling powers by manipulating the four manipulated variables available, namely, the compressor speed N, both expansion valve openings Av and Av,TES, and the TES pump. In Figure 6, the secondary mass flow that circulates through the TES tank m ̇ TES,sec is considered as a virtual manipulated variable, while the actual one is the TES pump speed/power. Anyway, for a certain required value of m ̇ TES,sec, a simple regulator is intended to drive the TES pump to actually provide the desired secondary mass flow. Therefore, four manipulated variables are available in the cooling power control, whereas only three references must be tracked. These three set points define the desired operating mode, according to Figure 5, in such a way that if one is zero, it involves one of the extensively manipulated variables (Av, Av,TES, or m ̇ TES,sec) also being zero. However, when the refrigerant circulates through the compressor (all operating modes considered in Figure 5 except mode 4), the degree of superheating at the compressor intake TSH must be positive, in order to avoid mechanical breakdowns. Since the fourth manipulated variable is thus responsible for getting the degree of superheating TSH over a certain security limit, in this case the control problem is fully actuated. Concerning the scheduler, given a certain cooling demand forecast, a NMPC-based strategy is applied. In view of the demand forecast and the expected energy prices through- out the day, an operating mode scheduling is proposed, and then the cooling power references are scheduled by solving a non-linear optimization problem. The simplified TES tank dynamic model proposed in Section 3.1 is used as the prediction model, since the scheduling strategy is focused on demand satisfaction and the TES tank cold-energy management, not on the actual production of the required powers, to be addressed by the cooling power controller. Nevertheless, some constraints on the scheduled powers (that turn out to be the decision variables of the optimization problem) must be imposed in order to ensure that the cooling power control problem is feasible and the references are indeed achievable. Additional constraints aimed to keep the PCM cylinders within latent zone are imposed, while the objective function of the optimization problem is based on economic and efficiency criteria. One important issue is related to time scales. The scheduling strategy is intended to be solved with a sampling time suitable to fit the demand profile, whereas the cooling power control is intended to be performed at the baseline sampling rate, fitting the fastest dynamics related to the refrigeration cycle. 4.2. Cooling Power Control As stated in Section 4.1, the cooling power control is a multivariable problem with four inputs (N, Av, Av,TES, and m ̇ TES,sec) and four outputs to be controlled (Q ̇ e,sec, Q ̇ TES,PDF Image | Refrigeration Systems with Thermal Energy Storage
PDF Search Title:
Refrigeration Systems with Thermal Energy StorageOriginal File Name Searched:
mathematics-10-03167.pdfDIY PDF Search: Google It | Yahoo | Bing
Turbine and System Plans CAD CAM: Special for this month, any plans are $10,000 for complete Cad/Cam blueprints. License is for one build. Try before you buy a production license. More Info
Waste Heat Power Technology: Organic Rankine Cycle uses waste heat to make electricity, shaft horsepower and cooling. More Info
All Turbine and System Products: Infinity Turbine ORD systems, turbine generator sets, build plans and more to use your waste heat from 30C to 100C. More Info
CO2 Phase Change Demonstrator: CO2 goes supercritical at 30 C. This is a experimental platform which you can use to demonstrate phase change with low heat. Includes integration area for small CO2 turbine, static generator, and more. This can also be used for a GTL Gas to Liquids experimental platform. More Info
Introducing the Infinity Turbine Products Infinity Turbine develops and builds systems for making power from waste heat. It also is working on innovative strategies for storing, making, and deploying energy. More Info
Need Strategy? Use our Consulting and analyst services Infinity Turbine LLC is pleased to announce its consulting and analyst services. We have worked in the renewable energy industry as a researcher, developing sales and markets, along with may inventions and innovations. More Info
Made in USA with Global Energy Millennial Web Engine These pages were made with the Global Energy Web PDF Engine using Filemaker (Claris) software.
Sand Battery Sand and Paraffin for TES Thermo Energy Storage More Info
CONTACT TEL: 608-238-6001 Email: greg@infinityturbine.com (Standard Web Page)