Unit Operation and Process Material and Energy Balance

1. Unit Operation and Process Material and Energy Balance WideliaIkaPutri, S.T.P., M.Sc.

2. Basic Principles • The mass and energy going into the box must balance with the mass and energy coming out. • The law of mass conservation states that mass can’t be created nor destroyed. • The law of energy conservation states that energy can’t be created nor destroyed.

3. Mass Conservation Milk X kg So: Milk mass = skim milk mass + cream milk mass X kg/minute = A kg/minute + B kg/minute Skim milk A kg Centrifugal separator Cream milk B kg

4. Energy Conservation Food (chemical energy) So: Chemical energy entering body = mechanical energy leaving body Body Mechanical energy

5. Energy Conservation Heating water So: The heat lost by the heating water = the heat gained by the milk + the heat lost from heat exchanger to its surroundings Heat exchanger Milk Heating milk cool water heat lost

6. Soal • Berapa air yang harusdiuapkandaripemekatanlar. Garam 5% menjadilar. Garam 20%? • Berapapenurunanberat yang terjadijikabahandikeringkandarikadar air 80% menjadikadar air 50%?

7. Soal • Tentukanjumlahdagingsapitidakberlemak (lean beef), dagingbabiberlemak (fat pork), dan air yang harusditambahkanuntukmembuatadonansosissebanyak 100 kg. dengansyarat : • Lean beef => lemak 14%, protein 19%, air 67% • Fat pork => lemak 89%, protein 3%, air 8% • Sosis => lemak 20%, protein 15%, air 65%

8. Soal 2. Padapembuatan jam buah-buahandigunakanperbandingan 45 buah : 55 gula. Untukmendapatkankonsistensi jam yang baik, jam harusmengandungpadatanterlarut 65%. Padaprosespembuatan jam terdiriataspencampuranbuahdanguladenganperbandingantersebut, penambahanpektin, pemekatancampurandalam evaporator vacumsehinggakandunganpadatanterlarut minimal 65%. Jumlahpektin yang diperlukandipengaruhiolehjumlahgula yang ditambahkan (untuk 100 kg guladiperlukanpektin 1kg). Apabilabuah yang digunakanmengandungpadatanterlarut 10%. Hitungberatbuah , guladanpektin yang diperlukan? Untukmembuat jam 100 kg, dianggapbahwapadatanterlarut yang dimaksudberasaldaribuahdangula (pektintidakdianggap).

9. Energy consumed Direct energy Fuel and electricity used on the farm, in transport, in factories, in storage, selling, etc. Indirect energy Energy which is used to build the machine, to make the packaging, to produce the electricity, etc.

10. Btu Energy unit joule kilocalories

11. 1 2 Latent Heat Is the heat required to change the physical state of material, at constant temperature. Sensible Heat The heat which when added or subtracted from food materials changes their temperature and thus can be sensed . Heat

12. Latent Heats (phase changes) • Vapourisation (L to V) • Melting (S to L) • Sublimation (S to V) Company Logo

13. Sensible heat • ‘Sensible’ heat – heat/enthalpy that must be transferred to raise or lower the temperature of a substance or mixture of substances. • Heat capacities/specific heats (solids, liquids, gases,vapours) • Use of mean heat capacities/specific heats over a temperature range • Use of simple empirical equations to describe the variation of Cp with T Company Logo

14. Uses • Heat required for a process • Rate of heat removal from a process • Heat transfer/design of heat exchangers • Process design to determine energy requirements of a process • Pump power requirements (mechanical energy balance) • Pattern of energy usage in operation • Process control • Process design & development Company Logo

15. Soal • Pengering casein mengkonsumsi gas alam 4m3/h dengannilaikalori 800kJ/mol. Jika input pengeringadalah 60 kg casein basah per jam, pengeringandarikadar air 55% menjadikadar air 10%, hitungkeseluruhanefisiensipanaspengering (hanyamenggunakanpanas latent)?

16. Soal 2. Autoclave berisi 100 kaleng sop. Dipanaskanmencapaisuhu 100oC. Kalengdidinginkanmencapai 40oC sebelummeninggalkan autoclave. Berapa air dingin yang dibutuhkanjika air masukpadasuhu 15oC dankeluarsuhu 35oC? ket: Panasspesifik sop 4,1 kJkg-1oC-1 & kaleng 0,5 kJkg-1oC-1 . Beratsetiapkaleng 60 g & berisi sop 0,45 kg. diasumsikanpanasdidinding autoclave1,6 x 104 kJ dantidakadapanas yang hilangmelaluidinding.

17. Soal • Sebuahpabrikminuman, menghasilkanprodukdengankadaralkohol 16% dankadargula 3%. Untukmembuatnyadiperlukancampuran: • Anggur 1 => kadaralkohol 14,6% & kadargula 0,2% • Anggur 2 => kadaralkohol 16,7% & kadargula 1,0% • Anggur 3 => kadaralkohol 17,0% & kadargula 12,0% biladiinginkanmembuat 100 kg produk, berapaberat masing2 minuman yang diperlukan?

18. ArigatouGozaimas