Basic Thermodynamics Lecture 7 Thermodynamic Cycles Thermodynamic Cycles

Basic Thermodynamics Lecture 7 Thermodynamic Cycles

Thermodynamic Cycles CYCLES When a system returns to its initial state at the end of the process, i. e. the process is a closed path, then that system is said to undergoes a cycles. Every cycles shall be described in two axis of thermodynamic properties. Cycle with 2 path Cycle with 4 path

Thermodynamic Cycles There are two thermodynamic cycles commonly and importantly to study since it has wide range of real life application. Power cycle Refrigeration & Heat Pump cycle Cycle with 2 path Cycle with 4 path

Thermodynamic Cycles Kesetimbangan energi dari suatu sistem yang mengalami siklus termodinamika dirumuskan sebagai berikut: Dimana adalah total perubahan energi yang terjadi pada sistem adalah total transfer energi dalam bentuk kalor adalah total transfer energi dalam bentuk kerja

Thermodynamic Cycles Karena sistem mengalami siklus, dimana sistem tersebut kembali ke keadaan awalnya (initial state), maka total perubahan energi yang terjadi adalah nol. Atau dengan kata lain, =0 Sehingga, Ini adalah penafsiran dari prinsip konservasi energi dan hukum pertama yang harus dipenuhi oleh semua siklus termodinamik, tanpa bergantung pada proses yang terjadi.

Thermodynamic Cycles POWER CYCLE • Is a system that deliver energy in form of net work to their surroundings during each cycle. • Qin represents the heat transfer of energy into the system from the hot body. • Qout represents heat transfer out of the system to the cold body.

Thermodynamic Cycles POWER CYCLE • Performansi dari sebuah siklus daya didefinisikan sebagai, “seberapa besar kerja yang dihasilkan dari kalor yang dimasukkan ke dalam sistem”. • Level performansi ini kemudian dinyatakan dalam suatu rasio yang disebut Efisiensi termal (thermal efficiency) suatu sistem.

Thermodynamic Cycles REFRIGERATION CYCLE • Tujuan dari siklus refrigirasi adalah mempertahankan temperature sistem berada di bawah temperatur lingkungannya. • Qin adalah energi masuk akibat perpindahan panas ke sistem dari reservoir temperatur rendah. • Qout adalah energi keluar akibat perpindahan panas dari sistem ke reservoir temperatur tinggi.

Thermodynamic Cycles REFRIGERATION CYCLE • The performance of refrigeration cycles can be described as the ratio of the amount of energy received by the system from the cold body, Qin, to the net work into the system to accomplish this effect, Wcycle. • Qout is discharged to the space in which the refrigerator is located. Wcycle is usually provided in the form of electricity to run the motor that drives the refrigerator

Thermodynamic Cycles HEAT PUMP CYCLE • The objective of a heat pump is to maintain the temperature within a building above that of the surroundings. • Qin is the energy transferred by heat into the system from the cold body. • Qout is the energy discharged by heat transfer from the system to the hot body.

Thermodynamic Cycles HEAT PUMP CYCLE • The performance of heat pumps can then be described as the ratio of the amount of energy discharged from the system to the hot body, Qout, to the net work into the system to accomplish this effect, Wcycle. • It can be seen that the value of γ is never less than unity. • The energy quantity Qin is normally drawn from the surrounding atmosphere, ground, or a nearby body of water. Wcycle is usually provided by