Introduction

According to Wikipedia.org, a heat pump is a device that provides heat energy from a source of heat to a destination called a “heat sink”. Heat pumps are designed to move thermal energy opposite to the direction of spontaneous heat flow by absorbing heat from a cold space and releasing it to a warmer one.

Figure 1.0: four phases in the thermodynamic cycle of the refrigerant fluid in a heat pump

In the compression phase of the fluid, in a gaseous state where pressure and temperature increase, absorbing heat. In the next phase, it passes through a condenser and the heat is released to the water or air used as carriers for heating the environments or the domestic hot water. In the third phase, the fluid - now returned to a liquid state - passes through an expansion valve (lamination process) which causes a drop in pressure and temperature. In the fourth and final phase, which is evaporation, it goes into a vaporous state, absorbing energy from the heat source.

Literature Review

A heat pump extracts heat from a reservoir with the temperature T1 through vaporisation of a coolant and transfer this heat to a reservoir with the temperature T2 through condensation of the coolant. As a result the temperature differential ΔT = (T2-T1) between the two reservoirs increases. A heat pump can be characterised by the efficiency ε which is greater than one. At first glance this seems to contradict the law of conservation of energy as the efficiency is the ratio of the quantity of heat ΔQ2 which is released by the heat pump to the reservoir with the temperature T2 to the applied electrical energy ΔW:

ε = ΔQ2/ ΔW

ε : efficiency of heat pump ΔQ2

: heat released to the reservoir with T2

ΔW : applied electrical energy to run the process

One of the aim of this experiment is to determine the efficiency ε of the heat pump as function of the temperature differential ΔT = (T2-T1). By determining the influence of the temperature differential between warm and cold reservoirs the importance of the heat reserves on the evaporation side for the efficiency is shown. The other aim of this experiment is to investigate the relationship between volume flowrate of water inlet and water outlet temperature.

Objectives:

1) To determining the efficiency of the heat pump as a function of the temperature differential.

2) To study the relationship between volume flowrate of water inlet and water outlet temperature.

Methodology:

Result: Experiment 1: Determine Efficiency of Heat Pump as a Function of Temperature Differential

Time, t (s) T1 T2 0306090120150180210240270300330360390420450580510540570600630660690720750780810840870900

930960990

Table 1: Temperature T1 and T2 as function of time t

Mass of water, m = Specific heat capacity of water c (H2O) =

Using formula:

ε= ΔT 2P . Δt

∗c∗m

ΔT/K ΔT2/K ε

Table 2:

Graph:Efficiency, ε

Figure 1: Efficiency of Heat Pump

ΔT/K