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MAE 107 Lab Report #3 Summer 2020

Name: Mohammed Alzayer

ID: 90083088

Instructor: Dr. Marco Maggia TA: Ivan Martinez

UCI CENTRAL PLANT (I) Summary This experiment was conducted with the goal of helping us to gain familiarity with the central plant that is located at the university and how it operates. The objectives of this lab were achieved by having an in depth look at the numerous components that make up the central plant that also aid in power plant modelling as well[ CITATION Lee19 \l 1033 ]. These components included the boilers, the heat exchangers, the cooling towers, the gas turbine, the types of fluids in the central plant just but to mention a few. I was able to draw a detailed schematic of the central plant that had both the high temperature water cycle as well as the cold-water production cycle and each water production cycle that operated separately. The schematics that I drew had the high-water temperature water supply and return, chilled water supply and return, boilers, gas turbine, deaerator just but to mention a few. On the schematic, I clearly identified the types of the water in the plant, the high temperature water, chilled water, cooling tower water, the supply and return waters that was used in the plant. The subsequent questions regarding the experiment were also answered. In conclusion, it is worth noting that this lab was very insightful in the sense that I was able to learn much more about the central plant that is in use at the campus and how it operates, hence the lab was a success.

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Questions 2. Complete schematics of the central plant The image below shows UCI central plant schematic diagram

Figure 1: UCI central plant schematic diagram The figure below shows the complete schematic of the central plant that consists of high temperature water production cycle

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Figure 2: high temperature water production cycle The figure below shows the cold-water production cycle

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Figure 3: cold water production cycle ABBREVIATIONS HPS HTWR HTWS Ex HTW CTWS CTWR CWR CWS

High Powered Steam Hot tower water return Hot tower water supply Exhaust gas Hot Temperature water Cold tower water supply Cold tower water return Cold Water Return Cold Water Supply

3. Is the steam generated in the boilers saturated or super-heated? How can you tell (without instruments)? [5 points] The steam generated is saturated steam. The steam can be said to be saturated or superheated by checking the operational temperature of the boiler this is because the superheated steam requires a high temperature source.

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4. What will happen if the nitrogen-blanket pressure on the high temp water (HTW) line is too low? The two main functions of the nitrogen-blanketing are to prevent corrosion and to maintain high pressure. If the pressure of nitrogen-blanket is too low, the water would boil creating steam which is more difficult to pump, is destructive to the inner walls of the pipes and has a much lower heat capacity than liquid water. 5. Describe the purpose of the cooling towers. When are they used? How do they work? Sketch a cooling tower diagram to help describe their functioning The main purpose of a cooling tower is to cool down water that gets heated up in the condenser or any other industrial processes.

Figure 4: Schematic diagram of a cooling tower The hot water from the compressor is pumped through pipes into the top of the cooling tower. cooling tower nozzles are then used to spray the water onto the “fill media” which slows the water down and expose maximum amount of water surface area for the best air-water contact. That water is pumped through pipes directly into the cooling tower. Cooling tower nozzles are used to spray the water onto to the “fill media”, which slows the water flow down and

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exposes the maximum amount of water surface area possible for the best air-water contact. The water is exposed to air sucked by the cooling-tower fan as it flows throughout the cooling tower. The water thus losses heat to the air and the water losses by drift and evaporation is replaced with treated make-up water. 6. Why are heat exchangers used instead of directly heating the return HTW? The heat exchangers are used instead of directly heating the return HTW because they save on energy and therefore minimize on the operating costs[CITATION Abo17 \l 1033 ]. By capturing the required heat needed to heat the HTW and using to heat the return HTW the overall efficacy of the plant is also improved. 7. In the heat exchangers used to warm up the HTW, which fluids are on the tube and shell sides of the HXs? Following the same logic, deduce which fluids are on the tube and shell sides of the chillers’ condensers and evaporators. Condenser Tube side

- Cold Tower Water Supply

Shell side- Cold Tower Water Return

Hot Tower Water Return

Shell Side-Hot tower water supply

Evaporator Tube side

8. What is the main purpose of the Thermal Energy Storage (TES)? In the TES, why is the return CW at the top? TES act as a storage for cold water produced when the production cost is low and the demand is low. The water is cold water is stored to be used during the day when the demand is high. The cold water is placed on the top so that it is easier to transport in peak usage hours.

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9. Why are the chilled water pipes in the tunnel of a greater diameter than the hot water pipes? (Justify your answer using the appropriate equation(s) and numbers) HTW pipes have a smaller diameter than the CW ones. This because of the different volumetric flow rates and the different temperature gradient. The temperature gradient of the hot water is higher than the temperature gradient of the chilled water and the volumetric flow rate of hot water is less than that of chilled water. Given that; Q L =ρ V C V ΔT

Where; Q L is the heat load, V is the volumetric flowrate,

CV

is the specific heat,

ΔT

is the temperature. Gradient and

ρ

is the density. Assuming similar density, isochoric specific heat for hot

and cold water and an equal heat load rate: ΔT HTW ˃ ΔT CW

; ΔV CW ˃ ΔV HTW

10. What is the purpose of the steam manifold? The main use of the manifold is to remove the complexity posed by the engineering design, which it does by being a device that connects the many boilers to the co-gen system and that to the heat exchangers. The steam manifold provides a mechanism that is capable for the connections of multiple channels, it therefore making the overall system run better with reduced design description costs and lower installation costs.

References Abou Elmaaty, T., Kabeel, A., & Mahgoub, M. (2017). "Corrugated Plate heat exchanger review". Renewable and Sustainable Energy Review, 852-860.

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Lee, G. J. (2019). Modelling Power Plant and Electric grid dynamics with high renewable use and climate change in California.

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