Download Thermodynamics & Heat Transfer: Refrigeration Cycle - HCMUT 2016 and more Schemes and Mind Maps Thermodynamics in PDF only on Docsity! THERMODYNAMICS & HEAT TRANSFER Duration: 36 hours during 12 weeks (4 teaching units/week) - Week 1 8 : Thermodynamics + Week 8 : Midterm Exam - Week 9 12 : Heat Transfer Final Exam 20% 40% Instructor: HÀ ANH TÙNG – Department of Heat and Refrigeration Technology Instructor: Dr. Tung Ha – Anh HCMUT 2/2016 + Week 4 : Test 1 + Week 10 : Test 2 15% 10% - Week 9 13 : Experimental 15% 1 Objectives of the course to provide students with knowledge and skills required to apply the basic principles of thermodynamics and heat transfer to perform calculations and explain thermal engineering applications: Ex: - Thermal power plants - Refrigeration and air conditioning systems - Dryers, boilers 2/2016 Instructor: Dr. Tung Ha – Anh HCMUT - Internal combustion engines - Heat exchangers, etc. 2 CHAPTER 6 : Refrigeration Cycle 6.1 Introduction 6.2 Basic refrigeration cycle 5 2/2016 Instructor: Dr. Tung Ha – Anh HCMUT Part 1: THERMODYNAMICS 6 6.1 Introduction 2/2016 Instructor: Dr. Tung Ha – Anh HCMUT is the cycle applied in Air conditioners, Refrigerators, etc. What is Refrigeration? Refrigeration is the process of removing heat from one substance and transferring it to another substance. 7 2/2016 Instructor: Dr. Tung Ha – Anh HCMUT Evaporator refrigerant vapor mixture of liquid and vapor refrigerant B A air 10 2/2016 Instructor: Dr. Tung Ha – Anh HCMUT Compressor low-pressure refrigerant vapor from evaporator C B high-pressure refrigerant vapor to condenser 11 2/2016 Instructor: Dr. Tung Ha – Anh HCMUT Condenser C D refrigerant vapor liquid refrigerant outdoor air 12 2/2016 Instructor: Dr. Tung Ha – Anh HCMUT Refrigerants TABLES Some types of refrigerant: Fréon 22 (R-22) Ammonia (NH3) Fréon 134A (R-134A) Saturated Tables Superheated Tables Pure substance 15 2/2016 Instructor: Dr. Tung Ha – Anh HCMUT Energy transfer in refrigeration cycle 1-2: Adiabatic compression wmn 4 2 1 3 q1 2-3: Isobaric condensation 3-4: Constant enthalpy process ( i4 = i3 ) q2 4-1: Isobaric evaporation Compressor Expansion valve Evaporator Condenser 16 2/2016 Instructor: Dr. Tung Ha – Anh HCMUT Calculation of refrigeration cycle i log p * Example: p3 , T1 given, with R-22 refrigerant State 1: T1 R22 Saturated Table p1 and ii 1 ss 1 State 2: Superheated, having p2 = p3 s2 = s1 R-22 Superheated Table 2i 17 2/2016 Instructor: Dr. Tung Ha – Anh HCMUT Exercise 20 2/2016 Instructor: Dr. Tung Ha – Anh HCMUT Solution: Having: Refrigerant: R-22 p3 = 18 bar t1 = 10oC Cooling capacity = G*q41 = 10kW 1) Determine enthalpy at 1, 2, 3, 4 - From t1 , p3 known: 21 2/2016 Instructor: Dr. Tung Ha – Anh HCMUT 2) Condenser capacity: 2 3 Condenser )(321 kWiiGQ iwhich G (kg/s) is the flow rate of R-22 , determined from the evaporator capacity (cooling capacity): skg ii G / 10 41 )(10 41 32 1 kW ii ii Q 22 2/2016 Instructor: Dr. Tung Ha – Anh HCMUT
Trang Thai | Nhiét do Ap suat Entanpi Entropi D6 khé
°C bar kJ/kg kJ/(kg.K) %
1. 10 6 709,55 1,7510 -
2. 68,4 18 737,50 1,7510 -
3. 47 18 558,65 1,1941 0
4. 6 6 558,65 1,2230 25,85
3. XAc dinh nang suat lanh Qo (kW), nang sudt ngung ty Qx (kW), c6ng sudt may nén (kW),
hé s6 lam lanh.
Oy = Gari, —i,)=104,79 kW
Ox =Gan Ai, —i,)=124,2 kW
N =O, -Q, =19,41 kW
Q
eé=—=5,4
N
4. Xdc dinh luu lugng nuéec gidi nhiét qua binh ngung G, (kg/h).
__ %
"¢. At
pr
n
=4,945 kg/s =17.800 kg/h
25
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