Tomato soup is flowing through a double-pipe heat exchanger (3 cm ID, 4.2 cm OD), with saturated steam at 112°C on the outside of the pipe. The convective heat transfer coefficient between the soup to the pipe is 323 W/m² K and the convective heat transfer coefficient between the steam to the pipe is very large. The thermal conductivity of the soup and pipe are 0.89 W/m K and 15.6 W/m K, respectively.

1. For this system:

A. The overall heat transfer coefficient for the inside of the pipe is smaller than the overal heat transfer coefficient for the outside of the pipe

B. Since the convective heat transfer coefficient between the steam and the pipe is very large, U=h_i

_C. The steam provides heat by converting from vapor to liquid

D. The log mean temperature difference for co-current and counter-current flow are the same, regardless of the inlet and outlet temperatures of the soup

2.The temperature of the soup at a certain point in the pipe is 55°C. If the pipe wall is at the same temperature as the steam, what is the rate of heat transfer between the pipe wall and the soup in kW/m²?

3. If the heat exchanger is 70 m long, what is U_i?

Benzene and water are virtually immiscible. What is the bubble pressure of an overall mixture that is 50 mol% of each at 75°C?

Freeze drying is a technique for dehydrating substances at low temperatures, thereby avoiding the degradation that may accompany heating. The material to be dried is cooled to a temperature at which all of the water present turns to ice. The frozen substance is then placed in a vacuum chamber and may also be subjected to radiant or microwave heating; the ice in the food sublimes, and the vapor is carried off by the vacuum pump. Steaks are to be freeze-dried in a heated chamber at 1 torr (1 mm Hg). The steaks, which contain 72% water by mass, enter the chamber at 26°C at a rate of 50 kg/min. Of the water entering with the steaks, 96% leaves as a vapor at 60°C; the remainder leaves as a liquid with the steaks at 50°C.

(a) Use the heat capacity data given below and additional tabulated data for water to calculate the required heat input in kilowatts.

(Cp)ice =2.17 J/(g°C)

(Cp)dry meat =1.38 J/(g°C)

(b) When large temperature changes are not involved in a phase-change operation, a reasonable estimate of the required heat transfer rate may be obtained by neglecting contributions of temperature changes to the overall process enthalpy change (i.e., by taking only phase changes into account). Moreover, it is often reasonable to use any available values of latent heats, neglecting their dependence on temperature and pressure. In the case of the freeze-drying process, the approximation might be to calculate only the heat needed to melt all the water and vaporize 96% of it, using latent heats at the normal melting and boiling points (Table B.1) and neglecting the heat required to raise the temperature of the meat and water. What percentage error in the calculated value of Q_ would result from this approximation? Take the value determined in Part (a) to be exact.

(c) Many substances, such as food and drugs, spoil if exposed too long to high temperatures (which accelerate rates of degradation) or to liquid water (which provides an environment for growth of microbial species that cause degradation). Also, rates of evaporation and sublimation increase as BIOENGINEERING Problems 477 WEBC08 06/04/2015 22:38:24 Page 478 temperature increases and pressure decreases. Use those observations to construct a oneparagraph explanation of how freeze-drying works and the reason for each step of the process. (For example, why is the sublimation done in a vacuum chamber?) Your explanation should be clear to someone with a nontechnical or nonscientific background.

What is mass? What is inertia? What is the relationship between mass and inertia? What has more inertia: a kitten or an elephant? Why?

What are carbon nanotubes, what is graphene and what is fullerenes? What are their main similarities, differences and applications?

The irreversible elementary reaction 2A > B takes place in the gas phase in an isothermal tubular reactor. The feed is one mole of A per one mole of C, an inert. The entering temperature and pressure are 427°C and 10 atm, respectively. The gas constant R = 0.08206 atm · L/mol · K.

(a) Determine the concentration of A at the entrance to the reactor.

(b) If C_A0 = 1.0 mol/L, what is the concentration of A at 90% conversion of A?

5. Now let’s say you would like to generate ozone in a container of oxygen gas at constant temperature and volume.

A) At equilibrium, what is the relation between the chemical potentials of ozone and oxygen?

B) Is the relevant equilibrium constant given by the usual ln Keq = ??G°/RT or instead by ln Keq = ??A°/RT? Here, ?A° is the change in Helmholtz free energy per mole of reaction. Justify your answer, either mathematically or conceptually. [Hint: The answer is not as trivial as it may seem. Think carefully about how the equilibrium constant was derived for reactions at constant temperature and pressure.]

A liquid mixture contains 60 wt% ethanol, 5 wt% of a dissolved solute, and the balance water. A stream of this mixture is fed to a distillation column operating at steady state. The streams emerging from the column have equal mass flow rates. The top stream contains 90 wt% ethanol with no solute.

Solve for all the mass fractions of the bottom stream and solve for the 3 mass flow rates

A very simple assumption for the specific heat of a crystalline solid is that each vibrational mode of the solid acts independently and is fully excited and thus c_v = 3N_A k_B = 24.9 c v ​ =3N A ​ k B ​ =24.9 kJ/(kmol\cdot⋅K). This is called the law of Dulong and Petit. Calculate the Debye specific heat (in units of kJ/(kmol\cdot⋅K) of the diamond at room temperature, 298 K. Use a Debye temperature of 2219 K.

Within the next decade, hydrogen fuel cell technology may emerge as a popular engine alternative within the automotive industry. Hydrogen gas storage technology, which remains a key issue to public safety, is continuing to advance. However, recent research has shown that polymer tanks that are reinforced with carbon fiber can achieve operating pressures above 50 MPa. For this example, consider a hydrogen refueling station that (for safety reasons) dispenses hydrogen gas to vehicles at a constant 20 MPa. Your car has a 65 L fuel tank. When you pull up to the station, your tank is at a pressure of 200 kPa (absolute). You may assume that the temperature of the hydrogen supply (of the refueling station), as well as the initial temperature of your tank are both at 300 K.

(a) If you add a mere 70 grams of hydrogen into your tank, what is the temperature rise inside of your fuel tank?

106.8 K

(b) After that little bit of hydrogen is added, what is the new pressure within your tank?

2077.6 kPa

(c) If instead of just adding a little fuel, you decide to fill up, how much hydrogen will fit in your tank? **Note: "Filling up" means you hold down the handle until no more fuel will flow into your tank. This happens when your tank pressure reaches the pressure of the hydrogen dispenser (20 MPa).

.737 kg

(d) What is the temperature within your tank after the fillup?

427.4 K

*** these are the answers i got but they are not correct

Suppose the Kelvin temperature (as measured by a reliable sensor) of a 9.0000 mol sample of gas in a rigid 5L tank is doubled. It is observed that the pressure increased to 2.1 times its original value. Which of the following statements could explain the observed result. (select all that apply)

No gas escapes and the gas obeys the ideal gas law.

The pressure reading for the final pressure is too high due to instrument malfunction

Some of the gas reacts with impurities in the tank so that the net moles of gas is unchanged

The pressure reading for the final pressure is too low due to instrument malfunction

Some of the gas reacts with impurities in the tank to form additional total moles of gas

Some gas leaks into the tank during heating assuming P is less than external pressure

Some gas escapes the tank during heating assuming P is greater than external pressure

Some of the gas reacts with impurities in the tank to reduce the total moles of gas

Calculate W,Q, Change of U, change of H ,and Change of S for the following two separate processes involved one mole of ideal gas(Cp= 3.5R) with the same initial state at 100kpa and 300k

A) the gas expands adiabatically and mechanical reversibly to 20kpa.

B) the gas expands to the same final state as process a) but it expands irreversibly with an efficiency of 60% compared with the reversible process a)

What are the two main functions of SDS (sodium dodecyl sulfate) in an SDS-PAGE experiment? Explain each function.

Suppose you’re building a vacation cottage up in the Rocky Mountains and you are concerned about the depth at which a new water line should be buried to avoid freezing during the cold winter weather. The soil there is dry and homogenous with a thermal diffusivity of 0.02 ft2/hr and a thermal conductivity of0.48 Btu/ ft hr °F . Suppose the initial temperature is 45 °F everywhere. At t=0, a very strong cold front moves in and the ambient temperature drops to –15 °F, and remains there for 48 hrs. How deep should the water line be so that the soil around the pipe does not fall below 30 °F during this period? Also, what is the heat flux at that depth at t=48 hrs?