Page 141 - Low Temperature Energy Systems with Applications of Renewable Energy

130 Low-Temperature Energy Systems with Applications of Renewable Energy

3. What heat sources are used as reserve and peak ones in systems with the HP?
4. Name the components of heat losses of indoor pools.
5. What factors influence the amount of moisture evaporating into the indoor pool premises?
6. Name the value of heat transfer coefficients from air to the surface of water in the pool in the
day time and at night.
7. Explain the scheme of the series use of heat recovery units and HPs.
8. How does the humidity in the pool decrease when using the HP?
9. Name the loss of heat per square meter of the outdoor pool.
10. Why are HPs more cost effective when used as air conditioners in summer?
11. What are the advantages and disadvantages of centralized heat supply using the HPs in
hospitals.
12. What are specific factors of using HPs in public buildings.
13. What is the essence of heat-pump-recovery systems of ventilation?
14. Explain the value of the coefficient of recovery and multiplicity of ventilation.
15. In which cases is recirculation of air in ventilation systems used?
16. Explain the operation of the air heating circuit with the HP.
17. What is more effective - heat recovery or recirculation of air in ventilation systems with the
HP?
18. What is the advantage of using heat pump stations with centralized heat supply?
19. Explain the advantages of the series connection of HP condensers in the heat pump station.
20. Show the processes of the absorption refrigerating machine in the xh-diagram
(concentration-enthalpy).
21. How does the absorption refrigerating machine operate?
22. Compose the heat balance of the absorption refrigerating machine and determine the value
of the thermal coefficient?
23. How does the absorption refrigerating machine of periodic action operate?
24. How does the absorption refrigerating machine of continuous action operate?
25. Is the efficiency of the HPU a function of the heat source?
26. How do the temperatures of condensation and evaporation of the refrigerant affect the heat
pump COP?
27. Compare and discuss the energy efficiency of vapor compression and absorption heat
pumps.
28. Which component in a vapor-compression heat pump is responsible for heating a desired
space: (a) absorber; (b) condenser; (c) evaporator; (d) regenerator?
29. Which component in an absorption heat pump is responsible for heating a desired space:
(a) condenser and generator; (b) throttle and pump; (c) generator and regenerator;
(d) evaporator and absorber; (e) condenser and absorber?

Exercises

1. Using as examples of refrigerants CO 2 and R152a, determine the effect of these different
fluids on a heat pump COP?
2. The P-h diagram in the figure below indicates the cycle for a heat pump operating between
100 kPa and 1000 kPa R152a is the refrigerant (Fig. 3.E1).
Part A. The compression work (kJ/kg) is nearest: (a) 117.7; (b) 110; (c) 100; (d) 130.
Part B. The cooling load (kJ/kg) is nearest: (a) 215; (b) 220; (c) 230; (d) 213.2.