- Đồ án môn học sấy bơm nhiệt bằng tiếng anh : Nguyên liệu sấy khóm (Dứa). - Bơm nhiệt được xem là một trong những hệ thống nhiệt có khả năng tiết kiệm năng lượng nhất hiện nay. Qua nhiều năm nghiên cứu và triển khai ứng dụng để hút ẩm và sấy lạnh thấy rằng bơm nhiệt có rất nhiều ưu điểm và rất có khả năng ứng dụng rộng rải trong điều kiện khí hậu nóng ẩm, phù hợp với thực tế tại Việt Nam, mang lại hiệu quả kinh tế kỹ thuật đáng kể. Sấy bơm nhiệt đặc biệt phù hợp với những sản phẩm cần bảo tồn tối đa màu, mùi và chất dinh dưỡng. Thường sấy ở nhiệt độ và tốc độ tác nhân sấy vừa phải. Đề tài này tính toán, thiết kế và chế tạo hệ thống sấy bơm nhiệt vật liệu sấy là lá Khóm
HCMC UNIVERSITY OF TECHNOLOGY AND EDUCATION FACULTY FOR HIGH QUALITY TRAINING PROJECT Topic: Calculation and design pineapple heat pump drying system Course: Refrigeration Technology Projects Instructor: Ph D Le Minh Nhut Student: Pham Van Long - 18147024 Ho Chi Minh city June, 2021 Feedback: Ho Chi Minh city, …/…/2021 Instructor’s signature Acknowledgement I have taken efforts in this project However, it would not have been possible without the kind support and help of many individuals and organizations I would like to extend my sincere thanks to all of them I am highly indebted to Ph.D Le Minh Nhut for their guidance and constant supervision as well as for providing necessary information regarding the project & also for their support in completing the project I would like to express my gratitude towards my all friends and lectures for their kind co-operation and encouragement which help me in completion of this project I would like to express my special gratitude and thanks to industry persons for giving me such attention and time My thanks and appreciations also go to my colleague in developing the project and people who have willingly helped me out with their abilities Ho Chi Minh City, June 2021 Student implementation: Phạm Văn Long Outline ACKNOWLEDGEMENT…………………….………………………….1 LIST OF FIGURES……………………………….…………………… LIST OF TABLES……………………………….………………………5 SYMBOLS AND ABBREVIATIONS…………………………… … Chapter 1: OVERVIEW………………………………………………….7 1.1 Reasons to choose the topic……………………………………… 1.2 The purposes of the topic………………………………………… 1.3 The overview of the pineapple…………………………………….9 Chapter 2: BASIC THEORETICAL ……………………………….… 13 2.1 General about drying technology……………………………… 13 2.1.1 Drying process……………………………………………… 13 2.1.2 Drying methods classified…………………………………….13 2.1.3 Drying agent………………………………………………… 16 2.1.4 Drying mode………………………………………………… 16 2.2 General about Heat pump-drying……………………………… 16 2.2.1 Principle diagram of Heat pump-drying………………………17 2.2.2 Coefficient of Heat pump-drying…………………………… 19 2.2.3 Basic ingredients of Heat pump-drying……………………….20 Chapter 3: CALCULATION AND DESIGN………………………… 22 3.1 Design plans……………………………….…………………… 22 3.1.1 Initial figures………………………….………………………22 3.1.2 Size of drying chamber……………………………………….22 3.2 Theoretical and practical drying process……….……………… 22 3.2.1 Represent the theoretical drying process on the I-d graph……22 3.2.2 Represent the practical drying process on the I-d graph…… 28 3.3 Parameters of the process……………………………………… 38 3.4 Establishment of cycle calculation diagram………….………… 39 3.5 Compressor calculation……………………………………… 41 3.6 Calculate resistance and fan…………………………………… 43 3.7 Select the condenser………………………………………….….48 Chapter ACTUAL EXPERIMENTAL SYSTEM……………………49 4.1 Heat pump system……………………………………………….49 4.2 Machine manufacturing results………………………………….51 4.3 The process of drying pineapple…………………………………52 Chapter 5: CONCLUSION AND RECOMMENDATION…………….55 5.1 Conclusion……………………………………………………… 55 5.2 Recommendation…………………….………………………… 55 REFERENCES……………… ……………………………………… 56 LIST OF FIGURES Figure 1.1 A pineapple on its parent plant……………………………………… 10 Figure 2.1 Equipment’s diagram……………………………………………… ….18 Figure 3.1 I-d graph represents the theoretical drying process……………… 23 Figure 3.2 Heat of actual drying……………………………………………………29 Figure 3.3 Structure of drying chamber………………………………………… 31 Figure 3.4 I-d graph showing the actual drying process…………………….….35 Figure 3.5 Thermodynamic cycle of the compressor………………………….…39 Figure 4.1 4NES-20Y 4NCS-20.2Y Bitzer piston compressor 20HP……… 49 Figure 4.2 Condenser and evaporator……………………………….……… ….50 Figure 4.3 Principal diagram of heat pump…………………………………… 50 Figure 4.4 Pineapple prepared………………………………………………… …52 Figure 4.5 Pineapple are arranged on trays………………………………… ….53 Figure 4.6: Electrical cabinets…………………………………………………… 54 LIST OF TABLES Table Nutrients in 100 grams(g) Pineapple……………………………….… 10 Table 3.1: state parameters at nodes……………………………………………….27 Table 3.2: Status parameter table at the actual drying process nodes…… …37 Table 3.3: Table of status parameters at nodes…………………………… … 40 Table 3.4: Indoor unit parameters………………………………………………….44 Table 3.5: Parameters of Condenser……………………………………………….46 Table 4.1: Technical parameters of heat pump dryer……………………………51 SYMBOLS AND ABBREVIATIONS V Volume, [m3] G Weight, [kg] φ Humidity, [%] p Specific weight, [kg/m3] t Temperature, [oC] d Vapor moisture content, [kg moisture/ kg kk] h enthalpy, [kJ/kg kk] λ Heat conductivity coefficient, [W/m.K] δ Thickness, [m] α Heat release coefficient, [W/m2.K] ν Velocity of drying agent, [m/s] cp Specific heat, [kJ/kg.K] k Heat transfer coefficient, [W/m2.K] Chapter 1: OVERVIEW 1.1 Reasons to choose the topic A Raw material drying Pineapple is a very delicious fruit and has a cooling effect in the summer, in addition it is also processed into dried food In 100g of the edible pineapple contains 91.5g of water The other ingredients are 6.5g glaucid; 15mg calcium mineral salts; 17mg phosphorus; iron 0.5mg; vitamin B1 0.08mg; beta-carotene 40mcg The pineapple nutrition in 100g provides 40kcal for the body The enzyme bromelain contained in the pineapple nutrition stimulates better digestion Bromelain neutralizes body fluids so that they not become too acidic So when we eat pineapple, we will reduce heartburn According to scientists also thanks to this substance, pineapple is also very good for the functioning of the pancreas According to research, the vitamin C content in pineapples provides 50% of the recommended daily amount of vitamin C So that pineapple has the effect of increasing the body's resistance It helps to prevent damage to cells, prevents some colds, flu, fever Pineapple contains many essential minerals: calcium, potassium, fiber, manganese, iodine In which, manganese is very good for bones and connective tissue With a glass of pineapple juice contains 73% manganese content According to a study in the US, manganese is very helpful in preventing osteoporosis in postmenopausal women B Heat Pump Drying technology Recently, it has been discovered that heat pump drying is an efficient method of drying for drying industries Heat pumps deliver more heat during the drying process than the work input to the compressor Heat pump drying is a more advanced method than the traditional Viet Nam industrial and agricultural drying methods, such as direct/indirect sunlight, wood burning, fossil fuel burning, electrical heating and diesel engine heating Heat pump dryers provide high energy efficiency with controllable temperature, air flow and air humidity and have significant energy-saving potential In the last decade the market for heat pump systems for water heating and space cooling/heating has grown in Viet Nam, but the development of heat pumps for industrial and agricultural drying is very slow The development of heat pump drying systems in Viet Nam is an efficient way to solve energy problems in drying applications as this technology is still in its infancy Thus, the discovery and widespread development of dehumidification and cold drying systems for food, post-harvest agricultural products, forest products and medicinal materials is an urgent requirement to encourage agricultural development and structural transformation crops, production of alternative goods imported and exported to the world market, saving energy, reducing investment capital and product costs Given the assignment of the topic as well as seeing the economic benefits of pineapple and the practical effects that heat pump drying technology brings in life, I would like to implement the topic "Design and manufacture of systems Pineapple heat pump drying " 1.2 The purposes of the topic - Learn about heat pump drying technology, drying method and equipment in heat pump drying system - Calculate and design pineapple heat pump drying system with a capacity of 200kg / batch - Fabrication of the heat pump drying system with calculated parameters - Testing and verifying the drying system on a real model λ= λi λw = 0,9.0,88 = 0,79 Theoretical scan volume: Vlt = Vtt λ = 0,027 0,79 = 0,0345m3/s = 142,2 m3/h Adiabatic compression: Ns = G.(i2 - i1) = 0,52.(411,32 – 401,67 ) =5,02 kW Performance indicator: Where, λw = b = 0,001; To Tk ηi = λw + b to ; to: boiling temperature, oC ηi = λw + b to = To Tk Compression indicator: + 0,001 to = 0,88 + 0,001 = 0,89 Ni = Effective compression work: Ne = Ni + Nms Ns 5,02 = = 5,64 kW ηi 0,89 With Nms calculated by: Nms = Vtt.pms Vtt: actual suction volume, Vtt = 0,027 m3/s; Pms : is the specific frictional pressure For the upstream Freon compressorPms = 0.019 ÷ 0.034 MPa, choose Pms = 0.03 MPa Nms = 0,027.0,03.1000 = 0,81 kW So, Ne = Ni + Nms = 5,64 + 0,81 = 6,45 kW Power supply capacity Nel: Nel = Ne ηel ηel : electric motor efficiency, ηel = 0,8 ÷ 0,95, choose ηel = 0,9 So, 42 Nel = Engine power: Nđc = (1,1 ÷ 2,1).Nel 6,45 = 7,167 kW 0,9 Choose a reserve factor of Nđc = 2.Nel = 2.7,167 = 14,334 kW Thus, select the 20 HP compressor 3.6 Calculation of resistance and calculation of fans The pressure loss due to friction of the air moving over the surface of the material is: ∆Pms l ρ ω2 =λ , N/m2 d Where : - Coefficient of frictional resistance; l - Length of material stacking, l = 1,6 m; dtd - Equivalent diameter of the ventilation gap between the two drying trays; - Air speed in the drying chamber, = m/s; - density of air at 450C; = 1,1105 kg/m3; ν = 17,32.10-6 m2/s Equivalent diameter of rectangular cross section: dtd = 1,3 Reynold’s standard: Re = (1.0,06)0,625 = 0,22 m (1 + 0,06)0,25 ω dtd 1.0,22 = = 0,13.105 < 105 v 17,32.10−6 Coefficient of frictional resistance: λ= 0,3164 0,3164 Re So friction loss through tray: 0,13.10 = 0,03 43 ∆Pms 1,6.1,1105 12 l ρ ω2 =λ = 0,03 = 0,12 N/m2 dtd 0,22.2 Friction loss through 30 trays: ∆Pms = 0,12.30 = 3,63 N/m2 Pressure loss due to local resistance: We have the actual volumetric flow of dry air calculated above as Vkktt = 1,62 m3/s, the path of the drying agent to the heat pump is 1m x 0.045m So the drying agent speed is: vo = Vkktt 1.62 = = m/s F 1.0,27 a Resistance through indoor unit Table 3.4: Indoor unit parameters Parameters Signal Unit Parameter Inside diameter of tube: dtr m 0,16 Outside diameter of tube: dng m 0,2 Horizontal pipe step: s1 m 0,52 Vertical pipe step: s2 m 0,48 Wings step: sc m 0,05 Blade thickness: δc m 0,01 Height of evaporator: W m 1,5 Length of evaporator: L m 0,6 Number of rows of pipes vertically: z1 row 20 Number of rows of pipes horizontal: z2 row Air velocity when passing through narrow slit of indoor unit: v= 1− vo dng h δc + s1 s1 sc Equivalent diameter dE: = = 16,25 m/s 0,2 (0,52 − 0,2) 0,01 1− + 0,52 0,52.0,05 44 dE = F0 dng + Fc F0 + Fc Fc nc F0: The outer surface area of the pipe between the blades corresponds to 1m of the pipe; F0 = π dng − Fc: Blade area of 1m pipe; δc 0,01 = π 0,2 − = 0,503 m2 /m sc 0,05 (s1 s2 − 0,785 dng ) (0,52.0,48 − 0,785 0,22 ) Fc = = = 8,728 m2 /m sc 0,05 nc: The number of blade on tube; nc = Thus, dE = L 600 = = 12 blades sc 50 0,503.0,2 + 8,728 0,503 + 8,728 8,728 2.12 = 0,581 m Average temperature of the air through the evaporator: tdl = 0,5.(35 + 20) = 27,5oC Looking up the table of physical parameters of the air at 27,5oC, we have: ρ1 = 1,172 kg/m3, v1 = 15,81.10-6 m2/s Reynolds standard of air through the evaporator: Rekk = v dE 16,25.0,581 = = 597169,5 v1 15,81.10−6 Resistance coefficient through the staggered winged tube beam: ξ = 0,72Rekk −0,245 s1 − dng +2 sc = 0,72 597169,5−0,245 = 0,28 0,52−0,2 0,05 +2 0,9 0,9 s1 − dng dng 0,52−0,2 0,9 0,2 0,9 s1 − dng s2 − dng −0,1 0,52−0,2 −0,1 0,48−0,2 So the resistance through the evaporator: 45 16,252 v2 ∆P1 = ξ ρ1 z2 = 0,28.1,172 = 87,6 N/m2 2 b Resistance through outdoor unit Table 3.5: Parameters of Condenser Parameters Inside diameter of tube: Outside diameter of tube: Horizontal pipe step: Vertical pipe step: Wings step: Blade thickness: Height of evaporator: Length of evaporator: Number of rows of pipes vertically: Number of rows of pipes horizontal: Signal dtr dng s1 s2 sc δc W L z1 z2 Unit m m m m m m m m Row Row Parameter 0,16 0,2 0,52 0,48 0,05 0,01 1,2 0,8 20 Air velocity when passing through narrow slit of outdoor unit: v= 1− vo dng h δc + s1 s1 sc = Equivalent diameter dE: dE = F0 dng + Fc F0 + Fc = 16,25 m/s 0,2 (0,52 − 0,2) 0,01 1− + 0,52 0,52.0,05 Fc nc F0: The outer surface area of the pipe between the blades corresponds to 1m of the pipe; F0 = π dng − δc 0,01 = π 0,2 − = 0,503 m2 /m sc 0,05 Fc: Blade area of 1m pipe; (s1 s2 − 0,785 dng ) (0,52.0,48 − 0,785 0,22 ) Fc = = = 8,728 m2 /m sc 0,05 46 nc: The number of blade on tube; nc = Thus, dE = L 800 = = 16 blades sc 50 0,503.0,2 + 8,728 0,503 + 8,728 8,728 2.16 = 0,505 m Average temperature of the air through the condenser: tdl = 0,5.(45 + 20) = 32,5oC Looking up the table of physical parameters of the air at 32,5, we have: ρ2 = 1,156 kg/m3, v2 = 16,173.10-6 m2/s Reynolds standard of air through the condenser: Rekk = v dE 16,25.0,505 = = 507404,3 v2 16,173.10−6 Resistance coefficient through the staggered winged tube beam: ξ = 0,72Rekk −0,245 s1 − dng +2 sc = 0,72 507404,3−0,245 = 0,29 0,52−0,2 0,05 0,9 +2 s1 − dng dng 0,9 0,9 s1 − dng s2 − dng 0,52−0,2 0,9 0,2 −0,1 0,52−0,2 −0,1 0,48−0,2 So the resistance through the condenser: ∆P2 = ξ ρ2 v2 16,252 z2 = 0,29.1,156 = 179,88 N/m2 2 We have the total local impedance: ΔPcb = ΔP1 + ΔP2 = 87,6 + 179,88 = 267,48 N/m2 So the total resistance of the system: ΔP = ΔPms + ΔPcb = 3,63 + 267,48 = 271,1 N/m2 We take the total resistance is 300 N/m2, Estimated the resistance of metal panel in the chamber We have the fan power calculated by the formula: 47 Nq = Vkk ΔP 1,62.2000 = 6,48 kW = 1000 ηq 1000.0,5 3.7 Select the condenser In order for the system to work stably, in addition to the main condenser which is responsible for heating the drying agent, the system is arranged with an additional sub-condenser that is responsible for discharging heat to the environment The auxiliary condenser is installed in series with the main condenser and placed outside the drying system When the temperature of the drying agent passing through the main condenser reaches the required value, the heat must be discharged to the outside environment through the auxiliary condenser To ensure the capacity of the refrigeration system, we choose the auxiliary condenser which is the condenser of the air conditioner with a compressor capacity of 20HP 48 Chapter ACTUAL EXPERIMENTAL SYSTEM 4.1 Heat pump system a Construction - Compressor: Figure 4.1: 4NES-20Y 4NCS-20.2Y Bitzer piston compressor 20HP + Type: 4NES-20Y 4NCS-20.2Y + Displacement(1450 RPM 50 HZ): 56.25m³/h + Displacement(1750 RPM 60 HZ): 67.89 m³/h + Max,pressure(LP/HP): 19/32 bar + Motor voltage(more on request): 380-420V Y-3-50 HZ + Max operating current: 33.2 A + No of cylinders: + Refregrant :R-22, R134, R410A + Weight(kg): 150 49 - Heat exchangers: Figure 4.2: Condenser and evaporator - Other equipment of the heat pump includes devices such as throttle cables, filters, electric motors, control devices and supporting devices b Operating priciple Figure 4.3: Principle diagram of heat pump 50 - Working principle: Heat pump drying is a drying method with a low-moisture drying agent The drying agent is brought into the indoor unit by the fan and cooled below the dew point temperature, so the moisture will condense and separate from the drying agent, the moisture content of the drying agent will decrease The drying agent at this time continues to be fed into the outdoor unit by the fan and heated to the drying temperature, then the drying agent will be put into the drying chamber, absorbing the moisture of the drying material, the moisture of the drying agent increases and is drawn by the fan to the indoor unit The process continues For the heat pump system, the refrigerant vapor, after leaving the evaporator, is drawn to the compressor to compress it into a high-pressure, high-temperature vapor The high pressure steam then enters the condenser which releases heat for the drying agent to condense into a liquid The high pressure liquid then passes through the throttle valve and into the evaporator In the evaporator, the liquid, which boils at low pressure and at low temperature, receives the heat of the agent to be cooled and turns into a vapor The steam is then drawn to the compressor, and the cycle continues 4.2 Machine manufacturing results Table 4.1: Technical parameters of heat pump dryer Technical parameters The weight of drying material per batch Drying chamber size Drying trays size The number of trays The weight of pineapple per tray Compressor capacity 200 kg 160cm x 100cm x 190cm 140cm x 90cm x 3cm 30 kg 20 HP 51 4.3 The process of drying pineapple - Step 1: Choose raw materials Pineapple must be fresh, ripe, not crushed, not too ripe or too young, discard damaged, crushed fruit The weight of pineapple needed for a batch of drying is 200kg Figure 4.4: Pineapple prepared - Step 2: Handling Purpose: + Recover the part used during processing and remove the damaged part, unused part to ensure the quality of the product after drying + Create uniformity for raw materials to reduce costs for batch of drying Implementation: Manual Requirements: no more impurities in the input drying material Fresh pineapple - Step 3: Wash and slice Purpose: clean raw materials, remove impurities (sand, dust, damaged parts) and microorganisms attached to the surface of raw materials Perform: 52 + Peel pineapple + Wash the pineapple with tap water, the ingredients must be submerged in water + Wash from to times until the water is clean, then take out and drain + Then slice thinly 2cm - 3cm Requirements: raw materials after washing are free of impurities, not crushed - Step 4: Put the materials on the tray Pineapple after being drained is arranged evenly into 30 trays, each tray has a weight of 7kg Figure 4.5: Pineapple are arranged on trays - Step 5: Carrying out drying + Power to the system, then the red light lights up indicating that there is power + Press the green button to start the system, the required drying temperature is 45oC + Every hour, we proceed to take the parameters once We get it within hours 53 Figure 4.6: Electrical cabinets 54 Chapter 5: CONCLUSION AND RECOMMENDATION 5.1 Conclusion Based on the results of theoretical calculations and experimental studies on the freeze-drying process of pineapple, we can draw the following conclusions: - Initially, built the technological process of pineapple drying on a theoretical heat pump dryer model - Determine the parameters of the drying process, thereby determining the advantages and disadvantages of the drying process - It is feasible to use heat pump refrigeration dryers to dry materials that require low temperatures, with strict requirements on quality such as color and taste The construction of a complete model can be applied to the actual production process - For heat pump dryers, determining the cooling capacity of the indoor unit plays a very important role in determining the optimal drying mode of the device, investment costs, and equipment operating costs 5.2 Recommendation - Because of the limited time to carry out the project, conducting model experiments with drying agent velocity parameters, as well as having not found the optimal drying temperature range for the materials, requires further research to build a standard model for many different drying materials - The combination of the drying process with the recovery of essential oils of the evaporating condensate drying materials in the indoor unit for some materials with a lot of essential oils also needs to be researched and developed - It is necessary to improve heat pump dryers capable of drying different types of drying materials to increase the working capacity of the machine 55 References [1] Trần Văn Phú Kỹ thuật sấy NXB Giáo dục, 2008 [2] Trần Văn Phú Tính tốn thiết kế hệ thống sấy NXB Giáo dục, 2002 [3] Hoàng Văn Chước Kỹ thuật sấy NXB Khoa học Kỹ thuật, 1999 [4] Nguyễn Đức Lợi Bài tập tính tốn kỹ thuật lạnh NXB Bách Khoa – Hà Nội, 2008 [5] Nguyễn Đức Lợi Hướng dẫn thiết kế hệ thống lạnh NXB Khoa học Kỹ thuật, 2007 [6] http://www.vnuhcm.edu.vn/Resources/file/TapChi/2008/07-2008.pdf [7] http://hueuni.edu.vn/portal/data/doc/tapchi/63_3.pdf [8] http://tailieu.yte.gov.vn/chi-tiet-tai-lieu/khao-sat-hoat-tinh-sinh-hoc-cay- diep-ca-houttuynia-cordata-thunb-trong-tai-thanh-pho-ho-chi-minh [9] http://vjs.ac.vn/index.php/vjbio/article/view/3878/3853 [10] http://www.lrchueuni.edu.vn/dongy/show_target.plx?url=/thuocdongy/D /DiepCa.htm&key=&char=D [11] https://vi.wikipedia.org/wiki/D%E1%BB%A9a#:~:text=Qu%E1%BA% A3%20d%E1%BB%A9a%20c%C3%B3%20h%C3%A0m%20l%C6%B0%E 1%BB%A3ng,vitamin%20C%20(d%E1%BB%A9a%20t%C3%A2y) [12] http://caroty.com/qua-dua-thanh-phan-dinh-duong-va-nhung-loi-ich/ 56